Water-processable silicone-containing prepolymers and uses thereof

ABSTRACT

The invention provide a class of water-processable polymerizable prepolymers which comprises (1) siloxane-containing monomeric units derived at least one siloxane containing monomer having one hydrophilic group or chain and/or polysiloxane-containing crosslinking units derived from at least one hydrophilized polysiloxane or chain-extended polysiloxane crosslinker; (2) hydrophilic monomeric units derived from one or more hydrophilic vinylic monomers; and (3) from about 0.05% to about 5% by weight of polymerizable units each having a pendant or terminal, ethylenically-unsaturated group and free of any polysiloxane segment. The prepolymer comprises from about 20% to about 50% by weight of silicone relative to the total weight of the prepolymer and has a high water solubility or dispersibility of at least about 5% by weight in water and suitable for making silicone hydrogel contact lenses.

This application is a divisional application of application Ser. No.13/253,186, filed Oct. 5, 2011, now U.S. Pat. No. 9,187,601, whichclaims the benefits under 35 U.S.C. §119 (e) of U.S. provisionalapplication Ser. No. 61/390,448 filed 6 Oct. 2010, 61/390,464 filed 6Oct. 2010 and 61/422,672 filed 14 Dec. 2010, incorporated by referencein their entireties

The present invention is related to a class of water-processablepolymerizable prepolymers and uses thereof. In addition, the presentinvention is related to a method for making silicone hydrogel contactlenses from a water-based lens-forming composition and to the contactlenses made according to the method of the invention.

BACKGROUND

In recent years, soft silicone hydrogel contact lenses become more andmore popular because of their high oxygen permeability and comfort.“Soft” contact lenses can conform closely to the shape of the eye, sooxygen cannot easily circumvent the lens. Soft contact lenses must allowoxygen from the surrounding air (i.e., oxygen) to reach the corneabecause the cornea does not receive oxygen from the blood supply likeother tissue. If sufficient oxygen does not reach the cornea, cornealswelling occurs. Extended periods of oxygen deprivation cause theundesirable growth of blood vessels in the cornea. By having high oxygenpermeability, a silicone hydrogel contact lens allows sufficient oxygenpermeate through the lens to the cornea and to have minimal adverseeffects on corneal health.

However, all commercially available silicone hydrogel contact lenses areproduced according to a conventional cast molding technique involvinguse of disposable plastic molds and a mixture of monomers and/ormacromers. There are several disadvantages with such conventionalcast-molding technique. For example, a traditional cast-moldingmanufacturing process must include lens extraction in whichunpolymerized monomers must be removed from the lenses by using anorganic solvent. Such lens extraction increases the production cost anddecreases the production efficiency. In addition, disposable plasticmolds inherently have unavoidable dimensional variations, because,during injection-molding of plastic molds, fluctuations in thedimensions of molds can occur as a result of fluctuations in theproduction process (temperatures, pressures, material properties), andalso because the resultant molds may undergo non-uniformly shrinkingafter the injection molding. These dimensional changes in the mold maylead to fluctuations in the parameters of contact lenses to be produced(peak refractive index, diameter, basic curve, central thickness etc.)and to a low fidelity in duplicating complex lens design.

The above described disadvantages encountered in a conventionalcast-molding technique can be overcome by using the so-calledLightstream Technology™ (CIBA Vision), which involves (1) a lens-formingcomposition being substantially free of monomers and comprising asubstantially purified prepolymer with ethylenically-unsaturated groups,(2) reusable molds produced in high precision, and (3) curing under aspatial limitation of actinic radiation (e.g., UV), as described in U.S.Pat. Nos. 5,508,317, 5,583,463, 5,789,464, and 5,849,810. Lenses can beproduced at relatively lower cost according to the LightstreamTechnology™ to have high consistency and high fidelity to the originallens design.

But, the Lightstream Technology™ has not been applied to make siliconehydrogel contact lenses. One potential issue in the manufacture ofsilicone hydrogel contact lenses based on Lightstream Technology™ isthat the silicone-containing polymerizable materials of a lensformulation are not soluble in water or ophthalmically compatiblesolvent (non-reactive diluent). As such a non-ophthalmically compatibleorganic solvent has to be used and a solvent exchange or hydrationprocess has been carried out in the production. Another potential issueis that the silicone-containing components of a lens formulation leftbehind on the mold surface may not be water soluble and anon-ophthalmically compatible organic solvent, not water, may have to beused to wash the reusable molds. However, use of organic solvents can becostly and is not environmentally friendly. A water-based mold washingsystem is desirable.

Therefore, there is still a need for a water-processable polymerizablesilicone-containing macromers or prepolymers and for washing, with awater-based system, reusable molds for making silicone hydrogel contactlenses according to the Lightstream Technology™. There is also a needfor new actinically-crosslinkable prepolymers suitable for makingsilicone hydrogel contact lenses with desired bulk and surfaceproperties according to the Lightstream Technology™.

SUMMARY OF THE INVENTION

The present invention, in one aspect, provides a water soluble orprocessable siloxane-containing prepolymer, which comprises: (1)siloxane-containing monomeric units and/or polysiloxane-containingcrosslinking units, wherein the siloxane-containing monomeric units arederived from one or more siloxane-containing vinylic monomers eachhaving at least one hydrophilic group and/or at least one hydrophilicpolymeric chains, wherein the polysiloxane-containing crosslinking unitsare derived from at least one hydrophilized polysiloxane crosslinkerand/or at least one chain-extended hydrophilized polysiloxanecrosslinker; (2) hydrophilic monomeric units derived from one or morehydrophilic vinylic monomers; (3) from about 0.05% to about 5% by weightof polymerizable units each having a pendant or terminal,ethylenically-unsaturated group and free of any polysiloxane segment;and (4) optionally hydrophobic units derived from at least onehydrophobic vinylic monomer free of silicone, wherein the prepolymercomprises from about 20% to about 50% by weight of silicone relative tothe total weight of the prepolymer and has a high water solubility ordispersibility of at least about 5% by weight in water, wherein theprepolymer is capable of being actinically crosslinked, in the absenceof one or more vinylic monomers, to form a silicone hydrogel contactlens having a water content of from about 20% to about 75% by weightwhen fully hydrated and an oxygen permeability (Dk) of at least about 40barrers.

In another aspect, the invention provides a method for making siliconehydrogel contact lenses, the method comprising a step of actinicallypolymerizing a lens-forming composition including an ophthalmicallycompatible solvent and a water-soluble or processablesilicone-containing polymerizable material dissolved or dispersedtherein.

In a further aspect, the invention provides silicone hydrogel contactlens, which comprises: a polymeric material that is obtained bypolymerizing, in a mold, a lens-forming composition including anophthalmically compatible solvent selected from the group consisting ofwater, 1,2-propylene glycol, a polyethyleneglycol having a molecularweight of about 400 Daltons or less, and combinations thereof, and awater soluble or processable silicone-containing polymerizable materialdissolved or dispersed therein.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Generally, the nomenclatureused herein and the laboratory procedures are well known and commonlyemployed in the art. Conventional methods are used for these procedures,such as those provided in the art and various general references. Wherea term is provided in the singular, the inventors also contemplate theplural of that term. The nomenclature used herein and the laboratoryprocedures described below are those well known and commonly employed inthe art.

An “ophthalmic device”, as used herein, refers to a contact lens (hardor soft), an intraocular lens, a corneal onlay, other ophthalmic devices(e.g., stents, glaucoma shunt, or the like) used on or about the eye orocular vicinity.

“Contact Lens” refers to a structure that can be placed on or within awearer's eye. A contact lens can correct, improve, or alter a user'seyesight, but that need not be the case. A contact lens can be of anyappropriate material known in the art or later developed, and can be asoft lens, a hard lens, or a hybrid lens. A “silicone hydrogel contactlens” refers to a contact lens comprising a silicone hydrogel material.

A “hydrogel” or “hydrogel material” refers to a crosslinked polymericmaterial which can absorb at least 10 percent by weight of water when itis fully hydrated.

A “silicone hydrogel” refers to a silicone-containing hydrogel obtainedby copolymerization of a polymerizable composition comprising at leastone silicone-containing vinylic monomer or crosslinker or at least oneactinically-crosslinkable silicone-containing prepolymer.

“Hydrophilic,” as used herein, describes a material or portion thereofthat will more readily associate with water than with lipids.

A “monomer” refers to a compound that can be polymerized chemically,actinically or thermally.

A “vinylic monomer”, as used herein, refers to a monomer that has onesole ethylenically unsaturated group and can be polymerized actinicallyor thermally.

The term “olefinically unsaturated group” or “ethylenically unsaturatedgroup” is employed herein in a broad sense and is intended to encompassany groups containing at least one >C═C< group. Exemplary ethylenicallyunsaturated groups include without limitation (meth)acryloyl

allyl, vinyl, styrenyl, or other C═C containing groups.

As used herein, “actinically” in reference to curing, crosslinking orpolymerizing of a polymerizable composition, a prepolymer or a materialmeans that the curing (e.g., crosslinked and/or polymerized) isperformed by actinic irradiation, such as, for example, UV irradiation,ionizing radiation (e.g. gamma ray or X-ray irradiation), microwaveirradiation, and the like. Thermal curing or actinic curing methods arewell-known to a person skilled in the art.

The term “(meth)acrylamide” refers to methacrylamide and/or acrylamide.

The term “(meth)acrylate” refers to methacrylate and/or acrylate.

A “hydrophilic vinylic monomer”, as used herein, refers to a vinylicmonomer which as a homopolymer typically yields a polymer that iswater-soluble or can absorb at least 10 percent by weight water.

A “hydrophobic vinylic monomer”, as used herein, refers to a vinylicmonomer which as a homopolymer typically yields a polymer that isinsoluble in water and can absorb less than 10 percent by weight water.

A “prepolymer” refers to a polymer that contains ethylenicallyunsaturated groups and can be polymerized actinically or thermally toform a polymer having a molecular weight larger than the startingprepolymer.

A “polymer” means a material formed by polymerizing/crosslinking one ormore vinylic monomers, crosslinkers and/or prepolymers.

“Molecular weight” of a polymeric material (including monomeric ormacromeric materials), as used herein, refers to the number-averagemolecular weight unless otherwise specifically noted or unless testingconditions indicate otherwise.

A “crosslinker” refers to a compound having at least twoethylenically-unsaturated groups. A “crosslinking agent” refers to acompound which belongs to a subclass of crosslinkers and comprises atleast two ethylenically unsaturated groups and has a molecular weight of700 Daltons or less.

A “polysiloxane” refers to a compound containing one sole polysiloxanesegment.

A “chain-extended polysiloxane” refers to a compound containing at leasttwo polysiloxane segments separated by a linkage.

A “polysiloxane crosslinker” refers to a compound having at least twoethylenically unsaturated groups and one sole polysiloxane segment.

A “chain-extended polysiloxane crosslinker” refers to a linearpolysiloxane compound which comprises at least two ethylenicallyunsaturated groups and at least two polysiloxane segments separated by alinkage.

A “polysiloxane vinylic monomer” refers to a vinylic monomer containingone sole ethylenically unsaturated group and one sole polysiloxanesegment.

A “chain-extended polysiloxane vinylic monomer” refers to a compoundwhich comprises one sole ethylenically unsaturated group and at leasttwo polysiloxane segments separated by a linkage.

A “bulkyl vinylic monomer” refers to a vinylic monomer having a bulkysubstitute group. Preferred bulky vinylic monomers include withoutlimitation N-[tris(trimethylsiloxy)silylpropyl]-(meth)acrylamide;N-[tris(dimethylpropylsiloxy)-silylpropyl](meth)acrylamide;N-[tris(dimethyl-phenylsiloxy)-silylpropyl](meth)acrylamide;N-[tris(dimethylethylsiloxy)silylpropyl](meth)acrylamide;N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)-2-methylacrylamide;N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)acrylamide;N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl]acrylamide;N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)-2-methylacrylamide;N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)acrylamide;N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]acrylamide;N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)-propyloxy)propyl]-2-methylacrylamide;N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methylacrylamide;N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;3-methacryloxy propylpentamethyldisiloxane;tris(trimethylsilyloxy)silylpropyl methacrylate (TRIS);(3-methacryloxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane);(3-methacryloxy-2-hydroxypropyloxy)propyltris(trimethylsiloxy)silane;3-methacryloxy-2-(2-hydroxyethoxy)-propyloxy)propylbis(trimethylsiloxy)methylsilane;N-2-methacryloxyethyl-O-(methyl-bis-trimethylsiloxy-3-propyl)silylcarbamate;3-(trimethylsilyl)propylvinyl carbonate;3-(vinyloxycarbonylthio)propyl-tris(trimethyl-siloxy)silane;3-[tris(trimethylsiloxy)silyl]propylvinyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl allyl carbamate;3-[tris(trimethylsiloxy)silyl]propyl vinyl carbonate;t-butyldimethyl-siloxyethyl vinyl carbonate; trimethylsilylethyl vinylcarbonate; trimethylsilylmethyl vinyl carbonate; t-butyl (meth)acrylate,cyclohexylacrylate, isobornyl methacrylate, a polysiloxane-containingvinylic monomer (having 3 to 8 silicone atoms), and combinationsthereof.

The term “fluid” as used herein indicates that a material is capable offlowing like a liquid.

A free radical initiator can be either a photoinitiator or a thermalinitiator. A “photoinitiator” refers to a chemical that initiates freeradical crosslinking/polymerizing reaction by the use of light. Suitablephotoinitiators include, without limitation, benzoin methyl ether,diethoxyacetophenone, a benzoylphosphine oxide, 1-hydroxycyclohexylphenyl ketone, Darocure® types of photoinitiators, and Irgacure® typesof photoinitiators, preferably Darocure® 1173, and Irgacure® 2959.Examples of benzoylphosphine oxide initiators include2,4,6-trimethylbenzoyldiphenylophosphine oxide (TPO);bis-(2,6-dichlorobenzoyl)-4-N-propylphenylphosphine oxide; andbis-(2,6-dichlorobenzoyl)-4-N-butylphenylphosphine oxide. Reactivephotoinitiators which can be incorporated, for example, into aprepolymer or can be used as a special monomer are also suitable.Examples of reactive photoinitiators are those disclosed in EP 632 329,herein incorporated by reference in its entirety. The polymerization canthen be triggered off by actinic radiation, for example light, inparticular UV light of a suitable wavelength. The spectral requirementscan be controlled accordingly, if appropriate, by addition of suitablephotosensitizers.

A “thermal initiator” refers to a chemical that initiates radicalcrosslinking/polymerizing reaction by the use of heat energy. Examplesof suitable thermal initiators include, but are not limited to,2,2′-azobis(2,4-dimethylpentanenitrile),2,2′-azobis(2-methylpropanenitrile), 2,2′-azobis(2-methylbutanenitrile),peroxides such as benzoyl peroxide, and the like. Preferably, thethermal initiator is 2,2′-azobis(isobutyronitrile) (AIBN).

A “polymerizable UV-absorbing agent” refers to a compound comprising anethylenically-unsaturated group and a UV-absorbing moiety which canabsorb or screen out UV radiation in the range from 200 nm to 400 nm asunderstood by a person skilled in the art.

A “spatial limitation of actinic radiation” refers to an act or processin which energy radiation in the form of rays is directed by, forexample, a mask or screen or combinations thereof, to impinge, in aspatially restricted manner, onto an area having a well definedperipheral boundary, as illustrated in U.S. Pat. Nos. 6,800,225,6,627,124, 7,384,590 and 7,387,759 (all of which are incorporated byreference in their entireties).

“Dye” means a substance that is soluble in a lens-forming fluid materialand that is used to impart color. Dyes are typically translucent andabsorb but do not scatter light.

A “pigment” means a powdered substance (particles) that is suspended ina lens-forming composition in which it is insoluble.

A “hydrophilic surface” in reference to a silicone hydrogel material ora contact lens means that the silicone hydrogel material or the contactlens has a surface hydrophilicity characterized by having an averagedwater contact angle of about 90 degrees or less, preferably about 80degrees or less, more preferably about 70 degrees or less, even morepreferably about 60 degrees or less.

An “average water contact angle” refers to a water contact angle(measured by Sessile Drop), which is obtained by averaging measurementsof individual contact lenses or samples of a silicone hydrogel material.

The term “post molding surface treatment” refers to a process which iscarried out after a contact lens is obtained by cast-molding of a lensformulation in a mold to render the surface of the contact lens morehydrophilic/wettable. For example, a post molding surface treatment canbe plasma treatment, chemical treatments, the grafting of hydrophilicmonomers or macromers onto the surface of a lens, physical deposition ofone or more layer of one or more hydrophilic polymers, crosslinking ahydrophilic coating onto a contact lens, etc.

An “antimicrobial agent”, as used herein, refers to a chemical that iscapable of decreasing or eliminating or inhibiting the growth ofmicroorganisms such as that term is known in the art. Preferred examplesof antimicrobial agent include without limitation silver salts, silvercomplexes, silver nanoparticles, silver-containing zeolites, and thelikes

“Silver nanoparticles” refer to particles which are made essentially ofsilver metal and have a size of less than 1 micrometer.

The term “soluble” in reference to a compound or material means that thecompound or material can be dissolved in a solvent to an extentsufficient to form a solution having a concentration of at least about1% by weight at room temperature (about 22° C. to about 28° C.).

The term “water solubility and/or dispersity” in reference to a compoundor material means the concentration (weight percentage) of the compoundor material dissolved and/or dispersed in water at room temperature(about 22° C. to about 28° C.) to form a transparent aqueous solution ora slightly hazy aqueous solution having a light transmissibility of 85%or greater in the range between 400 to 700 nm.

The term “water-processable” in reference to a silicone-containingpolymerizable material means that the silicone-containing polymerizablecomponent can be dissolved at room temperature (about 22° C. to about28° C.) in an ophthalmically compatible solvent to form a lens-formingcomposition (or formulation) having a light transmissibility of 85% orgreater in the range between 400 to 700 nm.

The term “ophthalmically compatible solvent” refers to a solvent whichmay be in intimate contact with the ocular environment for an extendedperiod of time without significantly damaging the ocular environment andwithout significant user discomfort. “Ocular environment”, as usedherein, refers to ocular fluids (e.g., tear fluid) and ocular tissue(e.g., the cornea) which may come into intimate contact with a contactlens used for vision correction, drug delivery, wound healing, eye colormodification, or other ophthalmic applications. Preferred examples ofophthalmically compatible solvents include without limitation water,1,2-propylene glycol, a polyethyleneglycol having a molecular weight ofabout 400 Daltons or less, and combinations thereof.

In accordance with the invention, the term “oxygen permeability” inreference to a contact lens means an estimated intrinsic oxygenpermeability Dk_(c) which is corrected for the surface resistance tooxygen flux caused by the boundary layer effect as measured according tothe procedures described in Example 1. The intrinsic “oxygenpermeability”, Dk, of a material is the rate at which oxygen will passthrough a material. Oxygen permeability is conventionally expressed inunits of barrers, where “barrer” is defined as [(cm³oxygen)(mm)/(cm²)(sec)(mm Hg)]×10⁻¹⁰.

The “oxygen transmissibility”, Dk/t, of a lens or material is the rateat which oxygen will pass through a specific lens or material with anaverage thickness of t [in units of mm] over the area being measured.Oxygen transmissibility is conventionally expressed in units ofbarrers/mm, where “barrers/mm” is defined as [(cm³ oxygen)/(cm²)(sec)(mmHg)]×10⁻⁹.

The “ion permeability” through a lens correlates with the IonofluxDiffusion Coefficient. The Ionoflux Diffusion Coefficient, D (in unitsof [mm²/min]), is determined by applying Fick's law as follows:D=−n′/(A×dc/dx)where n′=rate of ion transport [mol/min]; A=area of lens exposed [mm²];dc=concentration difference [mol/L]; dx=thickness of lens [mm].

The term “ethylenically functionalize” or ethylenicallyfunctionalization” in reference to a compound or polymer or copolymerhaving one or more reactive functional groups (e.g., amine, hydroxyl,carboxyl, isocyanate, anhydride, aziridine, azlactone, and/or epoxygroups) means a process or product thereof in which one or moreethylenically unsaturated groups are covalently attached to thefunctional groups of the compound or polymer or copolymer by reacting anethylenically functionalizing vinylic monomer with the compound orpolymer or copolymer under coupling reaction conditions.

An “ethylenically functionalizing vinylic monomer” throughout of thispatent application refers to a vinylic monomer having one reactivefunctional group capable of participating in a coupling (orcrosslinking) reaction known to a person skilled in the art. Any vinylicmonomer having a hydroxy, amino, carboxyl, epoxy, aziridine,acid-chloride, isocyanate group, which is coreactive with isocyanate,amine, hydroxyl, carboxy, or epoxy groups of a polysiloxane in theabsence or presence of a coupling agent (those described above), can beused in ethylenically functionalizing the polysiloxane. Examples ofethylenically-functionalizing vinylic monomers include withoutlimitation C₂ to C₆ hydroxylalkyl (meth)acrylate, C₂ to C₆ hydroxyalkyl(meth)acrylamide, allylalcohol, allylamine, amino-C₂-C₆ alkyl(meth)acrylate, C₁-C₆ alkylamino-C₂-C₆ alkyl (meth)acrylate, vinylamine,amino-C₂-C₆ alkyl (meth)acrylamide, C₁-C₆ alkylamino-C₂-C₆ alkyl(meth)acrylamide, acrylic acid, C₁-C₄ alkylacrylic acid (e.g.,methacrylic ethylacrylic acid, propylacrylic acid, butylacrylic acid),N-[tris(hydroxymethyl)-methyl]acrylamide, N,N-2-acrylamidoglycolic acid,beta methyl-acrylic acid (crotonic acid), alpha-phenyl acrylic acid,beta-acryloxy propionic acid, sorbic acid, angelic acid, cinnamic acid,1-carboxy-4-phenyl butadiene-1,3, itaconic acid, citraconic acid,mesaconic acid, glutaconic acid, aconitic acid, maleic acid, fumaricacid, aziridinyl C₁-C₁₂ alkyl (meth)acrylate (e.g., 2-(1-aziridinyl)ethyl (meth)acrylate, 3-(1-aziridinyl) propyl (meth)acrylate,4-(1-aziridinyl) butyl (meth)acrylate, 6-(1-aziridinyl) hexyl(meth)acrylate, or 8-(1-aziridinyl) octyl (meth)acrylate), glycidyl(meth)acrylate, vinyl glycidyl ether, allyl glycidyl ether,(meth)acrylic acid halide groups (—COX, X═Cl, Br, or I), C₁ to C₆isocyanatoalkyl (meth)acrylate, azlactone-containing vinylic monomers(e.g., 2-vinyl-4,4-dimethyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-dimethyl-1,3-oxazolin-5-one,2-vinyl-4-methyl-4-ethyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-butyl-1,3-oxazolin-5-one,2-vinyl-4,4-dibutyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-dodecyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-diphenyl-1,3-oxazolin-5-one,2-isopropenyl-4,4-pentamethylene-1,3-oxazolin-5-one,2-isopropenyl-4,4-tetramethylene-1,3-oxazolin-5-one,2-vinyl-4,4-diethyl-1,3-oxazolin-5-one,2-vinyl-4-methyl-4-nonyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-phenyl-1,3-oxazolin-5-one,2-isopropenyl-4-methyl-4-benzyl-1,3-oxazolin-5-one,2-vinyl-4,4-pentamethylene-1,3-oxazolin-5-one, and2-vinyl-4,4-dimethyl-1,3-oxazolin-6-one, with2-vinyl-4,4-dimethyl-1,3-oxazolin-5-one (VDMO) and2-isopropenyl-4,4-dimethyl-1,3-oxazolin-5-one (IPDMO) as preferredazlactone-containing vinylic monomers), and combinations thereof.

A “coupling reaction” is intended to describe any reaction between apair of matching functional groups in the presence or absence of acoupling agent to form covalent bonds or linkages under various reactionconditions well known to a person skilled in the art, such as, forexample, oxidation-reduction conditions, dehydration condensationconditions, addition conditions, substitution (or displacement)conditions, Diels-Alder reaction conditions, cationic crosslinkingconditions, ring-opening conditions, epoxy hardening conditions, andcombinations thereof. Non-limiting examples of coupling reactions undervarious reaction conditions between a pair of matching co-reactivefunctional groups selected from the group preferably consisting of aminogroup (—NHR′ as defined above), hydroxyl group, carboxylic acid group,acid halide groups (—COX, X═Cl, Br, or I), acid anhydrate group,aldehyde group, azlactone group, isocyanate group, epoxy group,aziridine group, thiol group, and amide groups (—CONH₂), are given belowfor illustrative purposes. A carboxylic acid group reacts with an aminogroup —NHR′ in the presence of a coupling agent—carbodiimide (e.g.,1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC),N,N′-dicyclohexylcarbodiimide (DCC),1-cylcohexyl-3-(2-morpholinoethyl)carbodiimide, diisopropylcarbodiimide, or mixtures thereof) to form an amide linkage; acarboxylic acid group reacts with an isocyanate group under heating toform an amide linkage; a carboxyl group reacts with an epoxy oraziridine group to form an ester bond; a carboxyl group reacts with ahalide group (—Cl, —Br or —I) to form an ester bond; an amino groupreacts with aldehyde group to form a Schiff base which may further bereduced; an amino group —NHR′ reacts with an acid chloride or bromidegroup or with an acid anhydride group to form an amide linkage(—CO—NR′—); an amino group —NHR′ reacts with an isocyanate group to forma urea linkage (—NR′—C(O)—NH—); an amino group —NHR′ reacts with anepoxy or aziridine group to form an amine bond (C—NR′); an amino groupreacts (ring-opening) with an azlactone group to form a linkage(—C(O)NH—CR₁R₂—(CH₂)_(r)—C(O)—NR′—); an amino group reacts with a halidegroup (—Cl, —Br or —I) to form an amine bond; a hydroxyl reacts with anisocyanate to form a urethane linkage; a hydroxyl reacts with an epoxyor aziridine or a halide group (—Cl, —Br or —I) to form an ether linkage(—O—); a hydroxyl reacts with an acid chloride or bromide group or withan acid anhydride group to form an ester linkage; an hydroxyl groupreacts with an azlactone group in the presence of a catalyst to form alinkage (—C(O)NH—CR₁R₂—(CH₂)_(r)—C(O)—O—); a thiol group (—SH) reactswith an isocyanate to form a thiocarbamate linkage (—N—C(O)—S—); a thiolgroup reacts with an epoxy or aziridine to form a thioether linkage(—S—); a thiol group reacts with an acid chloride or bromide group orwith an acid anhydride group to form a thiolester linkage; a thiol groupreacts with an azlactone group in the presence of a catalyst to form alinkage (—C(O)NH-alkylene-C(O)—S—); a thiol group reacts with a vinylgroup based on thiol-ene reaction under thiol-ene reaction conditions toform a thioether linkage (—S—); a thiol group reacts with an acryloyl ormethacryloyl group based on Michael Addition under appropriate reactionconditions to form a thioether linkage; and a 1,2- or 1,3-diol groupreacts with an acetaldehyde dimethylacetal group to form a cyclic acetallinkage.

It is also understood that coupling agents with two reactive functionalgroups may be used in the coupling reactions. A coupling agent havingtwo reactive functional groups can be a diisocyanate, a di-acid halide,a di-carboxylic acid compound, a di-acid halide compound, a di-azlactonecompound, a di-epoxy compound, a diamine, or a diol. A person skilled inthe art knows well to select a coupling reaction (e.g., anyone describedabove in this application) and conditions thereof to prepare apolysiloxane terminated with one or more ethylenically unsaturatedgroups. For example, a diisocyanate, di-acid halide, di-carboxylic acid,di-azlactone, or di-epoxy compound can be used in the coupling of twohydroxyl, two amino groups, two carboxyl groups, two epoxy groups, orcombination thereof; a diamine or dihydroxyl compound can be used in thecoupling of two isocyanate, epoxy, aziridine, carboxylic acid, acidhalide or azlactone groups or combinations thereof.

Any suitable C₄-C₂₄ diisocyanates can be used in the invention. Examplesof preferred diisocyanates include without limitation isophoronediisocyanate, tetramethylene diisocyanate, hexamethyl-1,6-diisocyanate,4,4′-dicyclohexylmethane diisocyanate, toluene diisocyanate,4,4′-diphenyl diisocyanate, 4,4′-diphenylmethane diisocyanate,p-phenylene diisocyanate, 1,4-phenylene 4,4′-diphenyl diisocyanate,1,3-bis-(4,4′-isocyanto methyl) cyclohexane, cyclohexane diisocyanate,and combinations thereof.

Any suitable diamines can be used in the invention. An organic diaminecan be a linear or branched C₂-C₂₄ aliphatic diamine, a C₅-C₂₄cycloaliphatic or aliphatic-cycloaliphatic diamine, or a C₆-C₂₄ aromaticor alkyl-aromatic diamine. A preferred organic diamine isN,N′-bis(hydroxyethyl)ethylenediamine, N,N′-dimethylethylenediamine,ethylenediamine, N,N′-dimethyl-1,3-propanediamine,N,N′-diethyl-1,3-propanediamine, propane-1,3-diamine,butane-1,4-diamine, pentane-1,5-diamine, hexamethylenediamine, andisophorone diamine.

Any suitable diacid halides can be used in the invention. Examples ofpreferred diacid halide include without limitations fumaryl chloride,suberoyl chloride, succinyl chloride, phthaloyl chloride, isophthaloylchloride, terephthaloyl chloride, sebacoyl chloride, adipoyl chloride,trimethyladipoyl chloride, azelaoyl chloride, dodecanedioic acidchloride, succinic chloride, glutaric chloride, oxalyl chloride, dimeracid chloride, and combinations thereof.

Any suitable di-epoxy compounds can be used in the invention. Examplesof preferred di-epoxy compounds are neopentyl glycol diglycidyl ether,1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether,glycerol diglycidyl ether, ethylene glycol diglycidyl ether, diethyleneglycol diglycidyl ether, polyethylene glycol diglycidyl ether, propyleneglycol diglycidyl ether, dipropylene glycol diglycidyl ether, andcombinations thereof. Such di-epoxy compounds are available commercially(e.g., those DENACOL series di-epoxy compounds from Nagase ChemteXCorporation).

Any suitable C₂-C₂₄ diols (i.e., compounds with two hydroxyl groups) canbe used in the invention. Examples of preferred diols include withoutlimitation ethylene glycol, diethylene glycol, triethylene glycol,tetraethylene glycol, polyethylene glycol, propylene glycol,1,4-butanediol, various pentanediols, various hexanediols, variouscyclohexanediols, and combination thereof.

Any suitable C₃-C₂₄ di-carboxylic acid compounds can be used in theinvention. Examples of preferred di-carboxylic acid compounds includewithout limitation a linear or branched C₃-C₂₄ aliphatic dicarboxylicacid, a C₅-C₂₄ cycloaliphatic or aliphatic-cycloaliphatic dicarboxylicacid, a C₆-C₂₄ aromatic or araliphatic dicarboxylic acid, a dicarboxylicacid which contains amino or imido groups or N-heterocyclic rings, andcombinations thereof. Examples of suitable aliphatic dicarboxylic acidsare: oxalic acid, malonic acid, succinic acid, glutaric acid, adipicacid, pimelic acid, suberic acid, azelaic acid, sebacic acid,undecanedioic acid, dodecanedioic acid, dimethylmalonic acid,octadecylsuccinic acid, trimethyladipic acid, and dimeric acids(dimerisation products of unsaturated aliphatic carboxylic acids, suchas oleic acid). Examples of suitable cycloaliphatic dicarboxylic acidsare: 1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylicacid, 1,3- and 1,4-cyclohexanedicarboxylic acid, 1,3- and1,4-dicarboxylmethylcyclohexane, 4,4′-dicyclohexyldicarboxylic acid.Examples of suitable aromatic dicarboxylic acids are: terephthalic acid,isophthalic acid, o-phthalic acid, 1,3-, 1,4-, 2,6- or2,7-naphthalenedicarboxylic acids, 4,4′-diphenyldicarboxylic acid,4,4′-diphenylsulphone-dicarboxylic acid,1,1,3-trimethyl-5-carboxyl-3-(p-carboxyphenyl)-indane, 4,4′-diphenylether-dicarboxylic acid, bis-p-(carboxylphenyl)-methane.

Any suitable C₁₀-C₂₄ di-azlactone compounds can be used in theinvention. Examples of such diazlactone compounds are those described inU.S. Pat. No. 4,485,236 (herein incorporated by reference in itsentirety).

The reactions conditions for the above described coupling reactions aretaught in textbooks and are well known to a person skilled in the art.

In general, the invention is directed to a class ofactinically-polymerizable silicone-containing prepolymers which have arelatively high water solubility and/or dispersity and suitable formaking silicone hydrogel contact lenses having a water content of fromabout 20% to about 75% by weight when fully hydrated, an oxygenpermeability (Dk) of at least about 40 barrers, and optionally (butpreferably) a hydrophilic surface characterized by an average watercontact angle of about 90 degrees or less.

There are several potential unique features associated with use ofprepolymers of the invention in making silicone hydrogel contact lens.First, a prepolymer of the invention can be used in preparing a siliconehydrogel lens formulation by dissolving or dispersing it in anophthalmically compatible solvent (e.g., water, 1,2-propylene glycol, apolyethyleneglycol having a molecular weight of about 400 Daltons orless, or a combination thereof).

Second, extractions of resultants silicone hydrogel contact lenses froma lens formulation comprising a prepolymer of the invention assilicone-containing polymerizable components can be carried out with theophthalmically compatible solvent if needed. Generally, extraction ofnon-volatile residuals from lenses made from polymerizable components ina lens formulation is required to remove unpolymerized ingredients inthe lens formulation. For silicone hydrogel lenses, the non-volatileextractables are usually performed using organic solvent due to thesolubility of silicone containing extractables which are not fullysoluble in aqueous solution. But, by using a prepolymer of the inventionas silicone-containing polymerizable materials in a lens formulation,water or other ophthalmically compatible solvents can be used as asolvent in the extraction process.

Third, if a lens formulation comprising a prepolymer of the invention assilicone-containing polymerizable components is used in cast molding ofsilicone hydrogel contact lenses and if reusable molds are used in thelens production based on the Lightstream Technology™, then the reusablemolds can be washed with water or other ophthalmically compatiblesolvent between consecutive molding cycles to remove silicone-containingpolymerizable materials of a lens formulation left behind on the moldsurface. Use of water can save the production cost and isenvironmentally friendly.

Fourth, a prepolymer can be used to produce silicone hydrogel contactlenses having a hydrophilic surface without any post molding surfacetreatment. It is known that a silicone hydrogel material typically has asurface or at least some areas of its surface, which is hydrophobic(non-wettable). Hydrophobic surface or surface areas will up-take lipidsor proteins from the ocular environment and may adhere to the eye. Thus,a silicone hydrogel contact lens will generally require a surfacemodification which is typically carried out after cast-molding of thelens. It is discovered that by having a balanced composition of thesilicone content and the content of the hydrophilic groups andhydrophilic polymer chains a prepolymer of the invention may have arelatively high water solubility and/or dispersity while providing asilicone hydrogel contact lens made therefrom with a relatively highoxygen permeability, a relatively high water content and a hydrophilicsurface without post molding surface treatment. It is believed that whensilicone portions of the polymer matrix of a silicone hydrogel made froma lens formulation containing a prepolymer of the invention migrate tothe lens surface, the pendant and terminal hydrophilic polymeric chainslinked directly to silicone through a short linkage may migrate to thelens surface and dangle out of the lens surface to form a hydrophilicsurface. Without post molding surface treatment, the lens productionprocess can be simplified and may be relatively more cost effective.

The present invention, in one aspect, provides a water soluble orprocessable siloxane-containing prepolymer, which comprises: (1)siloxane-containing monomeric units and/or polysiloxane-containingcrosslinking units, wherein the siloxane-containing monomeric units arederived from one or more siloxane-containing vinylic monomers eachhaving at least one hydrophilic moiety selected from the groupconsisting of a hydrophilic polymeric chain with a molecular weight ofup to about 10,000 Daltons (preferably about 7500 Dalton or less, morepreferably about 5000 Daltons or less), a hydroxyl group, an amidelinkage, a urethane linkage (or carbamate linkage), a diurethanelinkage, an oligo-ethyleneoxide linkage (i.e., composed about 2 to about12 ethyleneoxide units), a 2-hydroxy-substituted propyleneoxide linkage,and combinations thereof, wherein the polysiloxane-containingcrosslinking units are derived from at least one hydrophilizedpolysiloxane crosslinker and/or chain-extended hydrophilizedpolysiloxane crosslinker each having one or more pendant hydrophilicpolymer chains; (2) hydrophilic monomeric units derived from one or morehydrophilic vinylic monomers; (3) from about 0.05% to about 5%,preferably from about 0.1% to about 4%, more preferably from about 0.5to about 3% by weight of polymerizable units each having a pendant orterminal, ethylenically-unsaturated group and free of any polysiloxanesegment; and (4) optionally hydrophobic units derived from at least onehydrophobic vinylic monomer free of silicone, wherein the prepolymercomprises from about 20% to about 50%, preferably from about 25% toabout 45%, more preferably from 28% to about 40%, by weight of siliconerelative to the total weight of the prepolymer and has a high watersolubility or dispersibility of at least about 5%, preferably at leastabout 10%, more preferably at least about 20% by weight in water,wherein the prepolymer is capable of being actinically crosslinked, inthe absence of one or more vinylic monomers, to form a silicone hydrogelcontact lens having a water content of from about 20% to about 75%(preferably from about 25% to about 70%, more preferably from about 30%to about 65%) by weight when fully hydrated, an oxygen permeability (Dk)of at least about 40 barrers (preferably at least about 50 barrers, morepreferably at least about 60 barrers, and even more preferably at leastabout 70 barrers), and optionally (but preferably) a hydrophilic surfacecharacterized by an average water contact angle of about 90 degrees orless (preferably about 80 degrees or less, more preferably 70 degrees orless, even more preferably about 60 degrees or less) withoutpost-molding surface treatment.

The term “hydrophilic polymer chain” as used in this patent applicationrefers to a pendant and/or terminal polymer chain unless otherwisespecifically noted, which can be a linear or 3-arm (or Y-shape)hydrophilic polymer chain that comprises at least about 60%, preferablyat least about 70%, more preferably at least about 80%, even morepreferably at least about 90%) by weight of one or more hydrophilicmonomeric units selected from the group consisting of ethyleneoxides(—CH₂CH₂O—), (meth)acrylamide units, C₁-C₃ alkyl (meth)acrylamide units,di-(C₁-C₃ alkyl) (meth)acrylamide units, N-vinylpyrrole units,N-vinyl-2-pyrrolidone units, 2-vinyloxazoline units, 4-vinylpyridineunits, mono-C₁-C₄ alkoxy, mono-(meth)acryloyl terminatedpolyethyleneglycol units having a molecular weight of 2000 Daltons orless, di(C₁-C₃ alkyl amino)(C₂-C₄ alkyl) (meth)acrylate units, N—C₁-C₄alkyl-3-methylene-2-pyrrolidone units, N—C₁-C₄alkyl-5-methylene-2-pyrrolidone units, N-vinyl C₁-C₆ alkylamide units,N-vinyl-N—C₁-C₆ alkyl amide units, and combinations thereof. Preferably,the linear or 3-arm (or Y-shape) hydrophilic polymer chain comprisesbulky vinylic monomeric units (any one of those described above)

Such prepolymer can be obtained by first polymerizing a polymerizablecomposition including (a) at least one siloxane-containing vinylicmonomer having at least one hydrophilic moiety as described above)and/or at least one hydrophilized polysiloxane and/or chain extendedpolysiloxane crosslinker having one or more pendant hydrophilic polymerchains, (b) at least one hydrophilic vinylic monomer, (c) anethylenically functionalizing vinylic monomer having a first reactivefunctional group (other than ethylenically unsaturated group), (d) achain transfer agent with or without a second reactive functional group(other than thiol group), and (e) optionally a hydrophobic vinylicmonomer, to form a water-processable intermediary copolymer and then byethylenically functionalizing the intermediary copolymer with anethylenically functionalizing vinylic monomer having a third reactivefunctional group capable of reacting with the first and/or secondreactive functional group to form a linkage in a coupling reaction inthe presence or absence of a coupling agent to form the prepolymer,wherein the first, second and third reactive functional groupsindependent of one another are selected from the group consisting ofamino group, hydroxyl group, carboxyl group, acid halide group,azlactone group, isocyanate group, epoxy group, aziridine group, andcombination thereof. The general procedures for preparing amphiphilicprepolymers are disclosed in commonly-owned U.S. Pat. Nos. 6,039,913,6,043,328, 7,091,283, 7,268,189 and 7,238,750, 7,521,519; commonly-ownedUS patent application publication Nos. US 2008-0015315 A1, US2008-0143958 A1, US 2008-0143003 A1, US 2008-0234457 A1, US 2008-0231798A1, and commonly-owned U.S. patent application Ser. Nos. 12/313,546,12/616,166 and 12/616,169; all of which are incorporated herein byreferences in their entireties.

In accordance with the invention, any siloxane-containing vinylicmonomers can be used in the preparation of a water-processableprepolymer of the invention so long as they have at least onehydrophilic moiety selected from the group consisting of a hydrophilicpolymer chain with a molecular weight of up to about 10,000 Daltons orless (preferably about 7500 daltons or less, more preferably about 5000daltons or less, even more preferably about 2500 Daltons or less, mostpreferably about 1000 Daltons or less), a hydroxyl group, an amidelinkage, a urethane linkage (or carbamate linkage), a diurethanelinkage, an oligo-ethyleneoxide linkage (i.e., composed about 2 to 12ethyleneoxide units), a 2-hydroxy-substituted propyleneoxide linkage,and combinations thereof. Preferably, a siloxane-containing vinylicmonomer is represented by formula (1), (2), or (3)

in which

-   -   a1 is an integer from 1 to 5;    -   a2 is an integer of 1, 2 or 3;    -   b1 is an integer from 1 to 10;    -   d1 is an integer from 0 to 4;    -   e1 and e2 independent of each other are 0, 1, 2 or 3;    -   A₁, A₂, A₃, A₄, A₅, A₆, and A₇ independent of one another are        methyl or ethyl;    -   X₁ is hydrogen or methyl;    -   Y₁ is a radical of -M₁-X₂-M₂-X₃-M₃-X₄-M₄- in which M₁, M₂, M₃        and M₄ independent of one another are a direct bond, —CH₂—,        —C₂H₄—, —C₃H₆—, —CH₂—CH(OH)—CH₂—, or —(C₂H₄—O—)_(a3)- in which        a3 is an integer from 2 to 12, X₂, X₃, and X₄ independent of one        other are a linkage selected from the group consisting of a        direct bond, —O—, —NR′— in which R′ is H or C₁-C₄ alkyl,        —C(O)—NH—, —NH—C(O)—, —NH—C(O)—NH—, —O—C(O)—NH—, —S—,        —NH—C(O)—O—, —C(O)—O—, —O—C(O)—, —NH—C(O)—NH—Z₀—NH—C(O)—NH—,        —O—C(O)—NH—Z₀—NH—C(O)—O—, —O—C(O)—NH—Z₀—NH—C(O)—NH—, and        —NH—C(O)—NH—Z₀—NH—C(O)—O—, in which Z₀ is a linear or branched        C₂-C₁₂ alkylene divalent radical or a C₅-C₄₅ cycloaliphatic or        aliphatic-cycloaliphatic divalent radical optionally containing        therein one or more linkages of —O—, —NR′—, —S— and —C(O)—; D₁        and D₂ independently of each other are a divalent group of        formula (4)

-   -   -   in which A₈ and A₉ independent of each other are a direct            bond, a linear or branched C₁-C₁₀ alkylene divalent radical,            —(CH₂CH₂O)_(r1)—CH₂CH₂— in which r1 is an integer of 1 to            20, or a C₁-C₇ alkyleneoxy-C₁-C₇ alkylene divalent radical,            and R₁, R₂, R₃, R₄, R₅, R₆, R₇, and R₈, independently of one            another, are C₁-C₄-alkyl, -alk-(OCH₂CH₂)_(r2)—OR₆ in which            alk is C₁-C₆-alkylene divalent radical, R₉ is C₁-C₄ alkyl            and r2 is an integer from 1 to 20, m and p independently of            each other are an integer of from 0 to 150 and (m+p) is from            2 to 150;

    -   L₁, L₂, L₃, Y₂, Y₃, Y₄, Y₅, Y₆, and Y₇ independent of one        another are a direct bond or a divalent radical of        —Z₁—X₂—Z₂—X₃—Z₃—X₄—Z₄— In which X₂, X₃, and X₄ are as defined,        Z₁, Z₂, Z₃, and Z₄ independent of one other are is a direct        bond, a linear or branched C₁-C₁₂ alkylene divalent radical        optionally containing therein one or more linkages of —O—,        —NR′—, —S— and —C(O)—, a divalent radical of —CH₂—CH(OH)—CH₂— or        —(CH₂CH₂O)_(r1)—CH₂CH₂— with r1 as defined above, or a C₅-C₄₅        cycloaliphatic or aliphatic-cycloaliphatic divalent radical        optionally containing therein one or more linkages of —O—,        —NR′—, —S— and —C(O)—;

    -   B₁, B₂, B₃ and B₄ independent of one another are hydroxyl or        (preferably) a linear or 3-arm hydrophilic polymer chain having        a molecular weight of about 10,000 Daltons or less (preferably        about 7500 daltons or less, more preferably about 5000 daltons        or less, even more preferably about 2500 Daltons or less, most        preferably about 1000 Daltons or less) and comprising at least        about 60%, preferably at least about 70%, more preferably at        least about 80%, even more preferably at least about 90%) by        weight of one or more hydrophilic monomeric units selected from        the group consisting of ethyleneoxide units, (meth)acrylamide        units, C₁-C₃ alkyl (meth)acrylamide units, di-(C₁-C₃ alkyl)        (meth)acrylamide units, N-vinylpyrrole units,        N-vinyl-2-pyrrolidone units, 2-vinyloxazoline units,        4-vinylpyridine units, mono-C₁-C₄ alkoxy, mono-(meth)acryloyl        terminated polyethyleneglycol units having a molecular weight of        600 Daltons or less, di(C₁-C₃ alkyl amino)(C₂-C₄ alkyl)        (meth)acrylate units, N—C₁-C₄ alkyl-3-methylene-2-pyrrolidone        units, N—C₁-C₄ alkyl-5-methylene-2-pyrrolidone units, N-vinyl        C₁-C₆ alkylamide units, N-vinyl-N—C₁-C₆ alkyl amide units, and        combinations thereof, provided that at least one of B₂, B₃ and        B₄ is the linear or 3-arm hydrophilic polymer chain; and

    -   E₁ and E₂ independent of each another are an aliphatic or        cycloaliphatic or aliphatic-cycloaliphatic trivalent radical        which has up to 15 carbon atoms and can be interrupted by —O—,        —NR′—, —C(O)— and/or —S—.

Exemplary siloxane-containing vinylic monomers of formula (1) are thosedescribed in U.S. Pat. Nos. 4,711,943, 5,070,215, 5,998,498, 7,071,274,7,112,641 (herein incorporated by reference in their entireties). Thepreparation of such monomers is described in those patents. Preferredsiloxane-containing vinylic monomers of formula (1) include withoutlimitation N-[methylbis(trimethylsiloxy)silyl]propyl acrylamide,N-[methylbis(trimethylsiloxy)silyl]propyl methacrylamide,N-[tris(trimethylsiloxy)silyl]propyl acrylamide,N-[tris(trimethylsiloxy)-silyl]propyl methacrylamide, methylbis(trimethylsiloxy)silyl]propyl glycerol methacrylate (SiGMA), methylbis (trimethylsiloxy)-silylpropylglycerol acrylate,tris(trimethylsiloxy)silyl propyl glycerol methacrylate,tris(trimethylsiloxy)silylpropyl glycerol acrylate,3-[methyl-bis(trimethylsiloxy)silyl]propyl allyl carbamate,3-[methylbis(trimethylsiloxy)silyl]propyl vinyl carbamate,3-[tris(trimethylsiloxy)silyl]propyl allyl carbamate,3-[tris(trimethylsiloxy)silyl]propyl vinyl carbamate, or combinationsthereof.

Exemplary siloxane-containing vinylic monomers of formula (2) and (3)are those described in PCT patent application publication WO0059970,U.S. Pat. Nos. 5,981,615 and 5,760,100 (Macromer C), US patentapplication Nos. 61/390,448, and 61/390,464, and published US patentapplication Nos. US 2008/0234457 A1, US 2009/0143499 A1, US 2010/0120938A1, US 2010/0120939 A1, and US 2010/0298446 A1 (herein incorporated byreference in their entireties). The methods for preparing suchsiloxane-containing vinylic monomers are taught in those patentapplication publications and US patents above. Examples of preferredsiloxane-containing vinylic monomers of formula (2) and (3) includewithout limitation

In accordance with the invention, any hydrophilized polysiloxane orchain-extended polysiloxane crosslinkers can be used in the preparationof a water-processable prepolymer of the invention so long as theycomprise at least one pendant hydrophilic polymer chain. Preferably, thepolysiloxane-containing crosslinking units in a prepolymer of theinvention are derived from at least one hydrophilized polysiloxanecrosslinker and/or chain-extended hydrophilized polysiloxane crosslinkerof formula (7) or (8)

in which

-   -   d2, d3, d4, ω1, ω2, and ω3 independent of one another are an        integer from 0 to 20;    -   e3, e4, e5, e6, e7, υ1, υ2, υ3, υ4, and υ5 independent of one        other are 0, 1, 2 or 3 and (e3+e4+e5+e6+e7)≧1 and        (υ1+υ2+υ3+υ4+υ5)≧1;    -   X₁ is hydrogen or methyl;    -   D₃, D₄, D₅, D₆, D₇, D₈, D₉, and D₁₀ independently of one other        are a divalent group of formula (9)

-   -   -   in which Y₂₈ is as defined below, A₈, A₈′, A₉, and A₉′            independent of one other are a direct bond, a linear or            branched C₁-C₁₀ alkylene divalent radical,            —(CH₂CH₂O)_(r1)—CH₂CH₂— in which r1 is an integer of 1 to            20, or a C₁-C₇ alkyleneoxy-C₁-C₇ alkylene divalent radical,            and R₁, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₁′, R₂′, R₃′, R₄′, R₅′,            R₆′, R₇′, and R₈′ independently of one another, are            C₁-C₄-alkyl, -alk-(OCH₂CH₂)_(r2)—OR₉ in which alk is            C₁-C₆-alkylene divalent radical, R₉ is C₁-C₄ alkyl and r2 is            an integer from 1 to 20, f1 is an integer of 0 to 8, m1, m2,            p1 and p2 independently of each other are an integer of from            0 to 150, (m1+p1) and (m2+p2) independent of each other are            from 2 to 150;

    -   L₄, L₅, L₆, L₇, L₈, L₉, L₁₀, L₁₁, L₁₂, L₁₃, L₁₄, L₁₅, L₁₆, L₁₇,        Y₈, Y₉, Y₁₀, Y₁₁, Y₁₂, Y₁₃, Y₁₄, Y₁₅, Y₁₆, Y₁₇, Y₁₈, Y₁₉, Y₂₀,        Y₂₁, Y₂₂, Y₂₃, Y₂₄, Y₂₅, Y₂₆, Y₂₇, and Y₂₈ independent of one        another are a direct bond or a divalent radical of        —Z₁—X₂—Z₂—X₃—Z₃—X₄—Z₄— In which X₂, X₃ and X₄ independent of one        other are a linkage selected from the group consisting of a        direct bond, —O—, —NR′— in which R′ is H or C₁-C₄ alkyl,        —C(O)—NH—, —NH—C(O)—, —NH—C(O)—NH—, —O—C(O)—NH—, —S—,        —NH—C(O)—O—, —C(O)—O—, —O—C(O)—, —NH—C(O)—NH—Z₀—NH—C(O)—NH—,        —O—C(O)—NH—Z₀—NH—C(O)—O—, —O—C(O)—NH—Z₀—NH—C(O)—NH—, and        —NH—C(O)—NH—Z₀—NH—C(O)—O—, Z₀ is a linear or branched C₂-C₁₂        alkylene divalent radical or a C₅-C₄₅ cycloaliphatic or        aliphatic-cycloaliphatic divalent radical optionally containing        therein one or more linkages of —O—, —NR′—, —S— and —C(O)—, Z₁,        Z₂, Z₃ and Z₄ independent of one other are is a direct bond, a        linear or branched C₁-C₁₂ alkylene divalent radical optionally        containing therein one or more linkages of —O—, —NR′—, —S— and        —C(O)—, a divalent radical of —CH₂—CH(OH)—CH₂— or        —(CH₂CH₂O)_(d)—CH₂CH₂— with r1 as defined above, or a C₅-C₄₅        cycloaliphatic or aliphatic-cycloaliphatic divalent radical        optionally containing therein one or more linkages of —O—,        —NR′—, —S— and —C(O)—;

    -   B₅, B₆, B₇, B₈, B₉, B₁₀, B₁₁, B₁₂, B₁₃, and B₁₄ independent of        one another are hydroxyl or (preferably) a linear or 3-arm        hydrophilic polymer chain having a molecular weight of about        10000 Daltons or less (preferably about 7500 daltons or less,        more preferably about 5000 daltons or less, even more preferably        about 2500 Daltons or less, most preferably about 1000 Daltons        or less) and comprising at least about 60%, preferably at least        about 70%, more preferably at least about 80%, even more        preferably at least about 90%) by weight of one or more        hydrophilic monomeric units selected from the group consisting        of ethyleneoxide units, (meth)acrylamide units, C₁-C₃ alkyl        (meth)acrylamide units, di-(C₁-C₃ alkyl) (meth)acrylamide units,        N-vinylpyrrole units, N-vinyl-2-pyrrolidone units,        2-vinyloxazoline units, 4-vinylpyridine units, mono-C₁-C₄        alkoxy, mono-(meth)acryloyl terminated polyethyleneglycol units        having a molecular weight of 600 Daltons or less, di(C₁-C₃ alkyl        amino)(C₂-C₄ alkyl) (meth)acrylate units, N—C₁-C₄        alkyl-3-methylene-2-pyrrolidone units, N—C₁-C₄        alkyl-5-methylene-2-pyrrolidone units, N-vinyl C₁-C₆ alkylamide        units, N-vinyl-N—C₁-C₆ alkyl amide units, and combinations        thereof, provided that at least one of B₅, B₆, B₇, B₈, and B₉        and at least one of B₁₀, B₁₁, B₁₂, B₁₃, and B₁₄ are the linear        or 3-arm hydrophilic polymer chain;

    -   T₁, T₂, T₃, T₄, T₅, T₆, T₇, T₈, T₉, T₁₀, T₁₁, T₁₂, T₁₃, and T₁₄        independent of one another are an aliphatic or cycloaliphatic or        aliphatic-cycloaliphatic trivalent radical which has up to 15        carbon atoms and can be interrupted by —O—, —NR′—, —C(O)— and/or        —S—.

In accordance with the invention, a hydrophilized polysiloxanecrosslinker of formula (7) can be obtained from a hydroxy-containingpolysiloxane crosslinker (i.e., having one sole polysiloxane segment andtwo ethylenically unsaturated groups) by covalently attaching one ormore polyethyleneoxides or hydrophilic polymers of one or morehydrophilic vinylic monomers selected from the group consisting of(meth)acrylamide units, C₁-C₃ alkyl (meth)acrylamide units, di-(C₁-C₃alkyl) (meth)acrylamide units, N-vinylpyrrole units,N-vinyl-2-pyrrolidone units, 2-vinyloxazoline units, 4-vinylpyridineunits, mono-C₁-C₄ alkoxy, mono-(meth)acryloyl terminatedpolyethyleneglycol units having a molecular weight of 600 Daltons orless, di(C₁-C₃ alkyl amino)(C₂-C₄ alkyl) (meth)acrylate units, N—C₁-C₄alkyl-3-methylene-2-pyrrolidone units, N—C₁-C₄alkyl-5-methylene-2-pyrrolidone units, N-vinyl C₁-C₆ alkylamide units,N-vinyl-N—C₁-C₆ alkyl amide units, and combinations thereof, preferablyselected from the group consisting of N-vinylpyrrolidone, N,N-dimethyl(meth)acrylamide, (meth)acrylamide, N-vinyl formamide, N-vinylacetamide, N-vinyl isopropylamide, N-vinyl-N-methyl acetamide, andcombinations thereof, each of polyethylenoxide or hydrophilic polymercontaining one sole reactive functional group capable of participatingin a coupling reaction to form a covalent linkage, according to commonlyknown coupling reactions.

A hydroxyl-containing polysiloxane crosslinker having one solepolysiloxane segment can be obtained by ethylenically-functionalizingof:

-   (1) a di-epoxy-terminated polysiloxane by using an    ethylenically-functionalizing vinylic monomer selected from the    group consisting of C₂ to C₆ hydroxylalkyl (meth)acrylate, C₂ to C₆    hydroxyalkyl (meth)acrylamide, allyl alcohol, N—C₁-C₆    alkylamino-C₂-C₆ alkyl (meth)acrylate, N—C₁-C₆ alkylamino-C₂-C₆    alkyl (meth)acrylamide, acrylic acid, C₁-C₄ alkylacrylic acid, beta    methyl-acrylic acid (crotonic acid), alpha-phenyl acrylic acid,    beta-acryloxy propionic acid, sorbic acid, angelic acid, cinnamic    acid, 1-carboxy-4-phenyl butadiene-1,3, itaconic acid, citraconic    acid, mesaconic acid, glutaconic acid, aconitic acid, maleic acid,    fumaric acid, and combination thereof;-   (2) a di-hydroxyl-terminated, a di-N-alkylaminoalkyl-terminated, or    a di-carboxyl-terminated polysiloxane by using epoxy-containing    vinylic monomer (e.g., glycidyl (meth)acrylate, allyl glycidyl    ether, vinyl glycidyl ether, or a combination thereof);-   (3) a di-hydroxyl-terminated, a di-N-alkylaminoalkyl-terminated, or    a di-carboxyl-terminated polysiloxane by using an    ethylenically-functionalizing vinylic monomer selected from the    group consisting of C₂ to C₆ hydroxylalkyl (meth)acrylate, C₂ to C₆    hydroxyalkyl (meth)acrylamide, allylalcohol, N—C₁-C₆    alkylamino-C₂-C₆ alkyl (meth)acrylate, N—C₁-C₆ alkylamino-C₂-C₆    alkyl (meth)acrylamide, acrylic acid, C₁-C₄ alkylacrylic acid, beta    methyl-acrylic acid (crotonic acid), alpha-phenyl acrylic acid,    beta-acryloxy propionic acid, sorbic acid, angelic acid, cinnamic    acid, 1-carboxy-4-phenyl butadiene-1,3, itaconic acid, citraconic    acid, mesaconic acid, glutaconic acid, aconitic acid, maleic acid,    fumaric acid, and combination thereof, in the presence of a di-epoxy    compound (e.g., neopentyl glycol diglycidyl ether, 1,4-butanediol    diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol    diglycidyl ether, ethylene glycol diglycidyl ether, diethylene    glycol diglycidyl ether, polyethylene glycol diglycidyl ether,    propylene glycol diglycidyl ether, dipropylene glycol diglycidyl    ether, and combinations thereof) as a coupling agent;-   (4) a di-epoxy-terminated polysiloxane by using glycidyl    (meth)acrylate or allyl glycidyl ether or vinyl glycidyl ether in    the presence of a diol (e.g., hydroxy-terminated polyethyleneoxide    (HO-PEO-OH), hydroxy-terminated polypropyleneoxide (HO—PPO—OH),    hydroxy-terminated PEO/PPO block copolymer, ethylene glycol,    diethylene glycol, triethylene glycol, tetraethylene glycol,    polyethylene glycol, propylene glycol, 1,4-butanediol, various    pentanediols, various hexanediols, various cyclohexanediols, and    combination thereof) or di-carboxylic acid compound (e.g., oxalic    acid, malonic acid, succinic acid, glutaric acid, adipic acid,    pimelic acid, suberic acid, azelaic acid, sebacic acid,    undecanedioic acid, dodecanedioic acid, dimethylmalonic acid,    octadecylsuccinic acid, trimethyladipic acid,    1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid,    1,3- and 1,4-cyclohexanedicarboxylic acid, 1,3- and    1,4-dicarboxylmethylcyclohexane, 4,4′-dicyclohexyldicarboxylic acid,    and combinations thereof) as a coupling agent; or-   (5) combinations thereof.

Various polysiloxanes having two terminal functional groups selectedfrom the group consisting of hydroxyl groups (—OH), amino groups(—NHR′), carboxyl groups (—COOH), epoxy groups, isocyanate groups, thiolgroups, and combinations thereof can be obtained from commercialsuppliers (e.g., from Shin Etsu, Gelest, Inc, or Fluorochem). Otherwise,one skilled in the art will know how to prepare such difunctionalgroup-terminated polysiloxanes according to procedures known in the artand described in Journal of Polymer Science—Chemistry, 33, 1773 (1995)(herein incorporated by reference in its entirety). Examples ofcommercially available di-functional polysiloxane include withoutlimitation, di-epoxypropoxypropyl-terminated polysiloxane,di-hydroxyethoxypropyl-terminated polysiloxane,di-hydroxyl(polyethyleneoxy)propyl-terminated polysiloxane,dicarboxydecyl-terminated polysiloxane, dicarboxypropyl-terminatedpolysiloxane, di-caprolactone terminated polysiloxane,di-N-ethylaminopropyl terminated polysiloxane, and combinations thereof.

Examples of preferred hydroxyl-containing polysiloxane crosslinkershaving one sole polysiloxane segment are those that can be obtained fromthose commercial available di-functional polysiloxane by ethylenicallyfunctionalization, for example, including without limitation,α,ω-bis[3-(meth)acryloxy-2-hydroxypropyloxypropyl]-terminatedpolydimethylsiloxane,α,ω-bis[3-(meth)acryloxyethoxy-2-hydroxypropyloxypropyl]-terminatedpolydimethylsiloxane,α,ω-bis[3-(meth)acrylamidoethoxy-2-hydroxypropyloxypropyl]-terminatedpolydimethylsiloxane,α,ω-bis[3-(meth)acryloxypropoxy-2-hydroxypropyloxypropyl]-terminatedpolydimethylsiloxane,α,ω-bis[3-(meth)acrylamidopropoxy-2-hydroxypropyloxypropyl]-terminatedpolydimethylsiloxane,α,ω-bis[3-(meth)acrylamidoisopropoxy-2-hydroxypropyloxypropyl]-terminatedpolydimethylsiloxane,α,ω-bis(allyloxy-2-hydroxypropyl-oxyethoxypropyl)-terminatedpolydimethylsiloxane,α,ω-bis(vinyloxy-2-hydroxypropyl-oxyethoxypropyl)-terminatedpolydimethylsiloxane,α,ω-bis[(meth)acryloxy-2-hydroxypropyloxy-ethoxypropyl]-terminatedpolydimethylsiloxane,α,ω-bis[(meth)acryloxy-2-hydroxypropyl-N-ethylaminopropyl]-terminatedpolydimethylsiloxane,α,ω-bis[allyloxy-2-hydroxypropyl-N-ethylaminopropyl]-terminatedpolydimethylsiloxane,α,ω-bis[vinyloxy-2-hydroxypropyl-N-ethylaminopropyl]-terminatedpolydimethylsiloxane,α,ω-bis[(meth)acryloxy-2-hydroxypropyl-oxycabonylpropyl]-terminatedpolydimethylsiloxane,α,ω-bis[allyloxy-2-hydroxypropyl-oxycabonylpropyl]-terminatedpolydimethylsiloxane,α,ω-bis[vinyloxy-2-hydroxypropyl-oxycabonylpropyl]-terminatedpolydimethylsiloxane,α,ω-bis[(meth)acryloxy-2-hydroxypropyl-oxy-pentylcabonyloxyalkyl]-terminatedpolydimethylsiloxane,α,ω-bis[allyloxy-2-hydroxypropyl-oxy-pentylcabonyloxyalkyl]-terminatedpolydimethylsiloxane,α,ω-bis[vinyloxy-2-hydroxypropyl-oxy-pentylcabonyloxyalkyl]-terminatedpolydimethylsiloxane,α,ω-bis(allyloxy-2-hydroxypropyl-oxy(polyethylenoxy)propyl)-terminatedpolydimethylsiloxane,α,ω-bis(vinyloxy-2-hydroxypropyl-oxy(polyethylenoxy)propyl)-terminatedpolydimethylsiloxane,α,ω-bis[(meth)acryloxy-2-hydroxypropyl-oxy(polyethylenoxy)propyl]-terminatedpolydimethylsiloxane, a coupling product of C₂-C₄hydroxyalkyl(meth)acrylate or C₂-C₄ hydroxyalkyl(meth)acrylamide or(meth)acrylic acid withα,ω-bis(hydroxyethoxypropyl)-polydimethylsiloxane through a di-epoxycompound (e.g., 1,4-butanediol diglycidyl ether, 1,6-hexanedioldiglycidyl ether, glycerol diglycidyl ether, ethylene glycol diglycidylether, diethylene glycol diglycidyl ether, polyethylene glycoldiglycidyl ether, propylene glycol diglycidyl ether, dipropylene glycoldiglycidyl ether, or combinations thereof), and combinations thereof.

Various monofunctional terminated polyethyleneglycols (PEGs) orpolyethylenoxides (PEOs) can be obtained from commercial sources, e.g.,Shearwater Polymers, Inc., Polymer Sources™, Sigma-Aldrich, and PerstorpPolyols, Inc. Preferred monofunctional-terminated PEGs are those PEGswith one amino, hydroxyl, acid chloride, or epoxy group at one terminusand a methoxy or ethoxy group at the other terminus. Variousmonofunctional polyvinylpyrrolidones (PVPs) with one terminal hydroxy,carboxyl or thiol group can be obtained from commercial sources, e.g.,Polymer Sources™. It is understood that both the terms“polyethyleneglycol” and polyethyleneoxide” are interchangeable in thispatent application.

Monofunctional group-terminated hydrophilic polymers of one or morehydrophilic vinylic monomers selected from the group consisting ofN-vinylpyrrolidone, N,N-dimethyl (meth)acrylamide, (meth)acrylamide,N-vinyl formamide, N-vinyl acetamide, N-vinyl isopropylamide,N-vinyl-N-methyl acetamide, and combinations thereof can be preparedaccording to procedures similar to those described in U.S. Pat. No.6,218,508, herein incorporated by reference in its entirety. Forexample, one or more hydrophilic vinylic monomer without functionalgroup (i.e., primary amino group, hydroxyl group, isocyanate group,carboxyl group, or epoxy group) and a chain transfer agent (e.g.,2-mercaptoethanol, 2-aminoethanethiol, 2-mercaptopropinic acid,thioglycolic acid, thiolactic acid, or other hydroxymercaptanes,aminomercaptans, or carboxyl-containing mercaptanes) are copolymerized(thermally or actinically) in the presence or absence of an initiator toobtain a monohydroxy-, moncarboxyl-, or monoamine-terminated hydrophilicpolymer or copolymer. Generally, the molar ratio of chain transfer agentto that of one or more hydrophilic vinylic monomers is from about 1:5 toabout 1:100. The molar ratio of chain transfer agent to the hydrophilicvinylic monomer without functional group is selected to obtain a polymeror copolymer with a molecular weight of from about 500 to about 500,000,preferably from about 1000 to about 100,000, more preferably from about1500 to about 100,000 Daltons. Mono-epoxy-, mono-isocyanate-, ormono-acid chloride-terminated polymers or copolymers of one or morehydrophilic vinylic monomers can be prepared by covalently attachingepoxy, isocyanate, or acid chloride groups to the above-obtainedmonohydroxy- or monoamine-terminated polymers or copolymers of one ormore hydrophilic vinylic monomers according to any known procedures. Useof monofunctional group-terminated hydrophilic polymers with highermolecular weight may ensure that the interfacial film on a siliconehydrogel material or lens made from a prepolymer of the invention hasadequate thickness and coverage.

Alternatively, monofunctional group-terminated hydrophilic polymers canbe prepared by polymerizing the one or more hydrophilic monomers (freeof reactive functional group other than ethylenically unsaturated group)in the presence of a hydroxyl-, amine-, or carboxyl-containing freeradical initiator at a molar ratio of initiator to the hydrophilicmonomers of from about 1:30 to about 1:700. Examples of initiators withamine, hydroxyl, or carboxyl group are azo initiators, such as, e.g.,2,2′-Azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane}dihydrochloride,2,2′-Azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide,2,2′-Azobis[2-methyl-N-(2-hydroxyethyl)propionamide], or 2,2′-Azobis{2-methyl-N-[2-(1-hydroxybutyl)]propionamide},2,2′-Azobis(2-methylpropionamide)dihydrochloride,2,2′-Azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate, orthe likes.

A person skilled in the art will know well how to covalently attach amonofunctional group terminated PEG or hydrophilic polymer to one of thehydroxy groups of a hydroxy-containing polysiloxane crosslinker underwell known coupling reaction conditions as described above or taught intextbooks.

In accordance with the invention, a hydrophilized chain-extendedpolysiloxane crosslinker of formula (7) can be obtained from: (A) ahydroxy-containing chain-extended polysiloxane crosslinker (i.e., havingat least two polysiloxane segments and two ethylenically unsaturatedgroups) by covalently attaching one or more polyethyleneoxides orhydrophilic polymers of one or more hydrophilic vinylic monomersselected from the group consisting of N-vinylpyrrolidone, N,N-dimethyl(meth)acrylamide, (meth)acrylamide, N-vinyl formamide, N-vinylacetamide, N-vinyl isopropylamide, N-vinyl-N-methyl acetamide, andcombinations thereof, each of polyethylenoxide or hydrophilic polymercontaining one sole reactive functional group capable of participatingin a coupling reaction to form a covalent linkage, according to commonlyknown coupling reactions (described above); and/or (B) a di-functionalgroup terminated chain-extended polysiloxane comprising at least onependant hydrophilic polymer chain by ethylenical functionalization withan ethylenically functionalizing vinylic monomer described above.

A hydroxy-containing chain-extended polysiloxane crosslinker (i.e.,having at least two polysiloxane segments separated by a linkage) can beobtained by: (1) reacting at least one polysiloxane crosslinker havingone sole polysiloxane segment and two ethylenically-unsaturated groupswith at least one dimercapto compound or dimercaptan (i.e., a compoundhaving two thiol groups), under Michael Addition or thiol-ene reactionconditions, provided that at least one of the dimercaptan, thepolysiloxane crosslinker and polysiloxane vinylic monomer comprises atleast one, preferably at least two hydroxyl groups; and/or (2) reactingat least one di-thiol terminated polysiloxane having one solepolysiloxane segment with at least one crosslinking agent (i.e., acompound having two ethylenicallynically unsaturated groups and amolecular weight of 700 Daltons or less), under Michael Addition orthiol-ene reaction conditions, provided that at least one of thedi-thiol-terminated polysiloxane, the mono-thiol-terminated polysiloxaneand the crosslinking agent comprises at least one, preferably at leasttwo hydroxyl groups.

It is understood that a reaction for preparing a hydroxy-containingchain-extended polysiloxane crosslinker can be prepared in a one-potreaction. For example, a polysiloxane crosslinker can react with adimercaptan under Michael Addition or thiol-ene reaction conditions at amolar equivalent ratio of about 2:1 to form a chain-extendedpolysiloxane crosslinker having two polysiloxane segments linkedtogether through a linker derived from the dimercaptan. Alternatively,steps-wise reactions can be used. For example, in the first step, adimercaptan (or di-thiol-terminated polysiloxane) can be reacted with apolysiloxane crosslinker (or a crosslinking agent) under the MichaelAddition or thio-ene reaction conditions at a molar equivalent ratio ofabout 2:1 or higher to form a thiol-capped polysiloxane. In the secondstep, the polysiloxane crosslinker (or crosslinking agent) can bereacted with the thiol-capped polysiloxane under the Michael Addition orthio-ene reaction conditions at a molar equivalent ratio of about 2:1 orhigher to form a hydroxy-containing polysiloxane crosslinker havingthree (or two) polysiloxane segments. Addition step(s) of reactions canbe used to add additional polysiloxane segments in a hydroxy-containingpolysiloxane crosslinker.

Any dimercaptans having 2 to 24 carbon atoms can be used in theinvention to prepare a hydroxy-containing chain-extended polysiloxanecrosslinker. Examples of dimercaptans include without limitation C₂-C₁₂alkyl dimercaptans (e.g., ethyl dimercaptan, propyl dimercaptan, butyldimercaptan, pentamethylene dimercaptan, hexamethylene dimercaptan,heptamethylene dimercaptan, octamethylene dimercaptan, nonamethylenedimercaptan, decamethylene dimercaptan, or combinations thereof),ethylcyclohexyl dimercaptan, dipentene dimercaptan, benzenedithiol,methyl-substituted benzenedithiol, benzenedimethanethiol, glycoldimercaptoacetate, ethyl ether dimercaptan (diglycol dimercaptan),triglycol dimercaptan, tetraglycol dimercaptan, dimercaprol,dimercaptopropanol, dimercaptobutanol, dimercaptopentanol,dimercaptopropionic acid, dihydrolipoic acid, dithiothreitol,dimercaptosuccinic acid, and combinations thereof.

The preferred hydroxy-containing polysiloxane vinylic monomers orcrosslinkers described above can be used in preparing ahydroxy-containing chain-extended polysiloxane crosslinker. It isunderstood that various commercially-available polysiloxane crosslinkersterminated with two (meth)acryloyl, allyl, and/or vinyl groups and freeof hydroxyl group (e.g., from Gelest, Inc, or Fluorochem) can be used inthe preparation of a hydroxy-containing chain-extended polysiloxanevinylic monomer or crosslinker so long as that a dimercaptan contains atleast one hydroxyl group.

Any crosslinking agents can be used in the preparation of ahydroxy-containing chain-extended polysiloxane crosslinker of theinvention. Examples of preferred cross-linking agents include withoutlimitation tetraethyleneglycol di-(meth)acrylate, triethyleneglycoldi-(meth)acrylate, ethyleneglycol di-(meth)acrylate, diethyleneglycoldi-(meth)acrylate, bisphenol A dimethacrylate, vinyl methacrylate,ethylenediamine di(meth)acrylamide, glycerol dimethacrylate,allyl(meth)acrylate, N,N′-methylenebis(meth)acrylamide,N,N′-ethylene-bis(meth)acrylamide, N,N′-dihydroxyethylenebis(meth)acrylamide,1,3-bis(methacrylamidopropyl)-1,1,3,3-tetrakis(trimethylsiloxy)disiloxane,1,3-bis(N-(meth)acrylamidopropyl)-1,1,3,3-tetrakis-(trimethylsiloxy)disiloxane,1,3-bis(methacrylamidobutyl)-1,1,3,3-tetrakis(trimethylsiloxy)-disiloxane,1,3-bis(methacryloxyethylureidopropyl)-1,1,3,3-tetrakis(trimethylsiloxy)disiloxane,a product of diamine (preferably selected from the group consisting ofN,N′-bis(hydroxyethyl)ethylenediamine, N,N′-dimethylethylenediamine,ethylenediamine, N,N′-dimethyl-1,3-propanediamine,N,N′-diethyl-1,3-propanediamine, propane-1,3-diamine,butane-1,4-diamine, pentane-1,5-diamine, hexamethylenediamine,isophorone diamine, and combinations thereof) and epoxy-containingvinylic monomer (preferably selected from the group consisting ofglycidyl (meth)acrylate, vinyl glycidyl ether, allyl glycidyl ether, andcombinations thereof), combinations thereof. A more preferredcross-linking agent to be used in the preparation of ahydroxy-containing chain-extended polysiloxane crosslinker of theinvention is tetra(ethyleneglycol) diacrylate, tri(ethyleneglycol)diacrylate, ethyleneglycol diacrylate, di(ethyleneglycol) diacrylate,glycerol dimethacrylate, allyl(meth)acrylate, N,N′-methylenebis(meth)acrylamide, N,N′-ethylene bis(meth)acrylamide,N,N′-dihydroxyethylene bis(meth)acrylamide, or combination thereof.

In accordance with the invention, a hydroxy-containing chain-extendedpolysiloxane crosslinker can further be obtained by reactingethylenically functionalizing vinylic monomer having an amino (—NHR′),carboxyl or epoxy group with a di-functional chain-extended polysiloxanehaving two terminal functional groups selected from the group consistingof amino group, carboxyl group, epoxy group, and combination thereof, inthe presence or absence of a coupling agent selected from the groupconsisting of diamine, di-epoxy and di-carboxylic acid compound, whereinthe di-functional chain-extended polysiloxane is obtained by reactingone or more di-functional polysiloxanes each having two terminal amino,epoxy or carboxyl groups in the presence or absence of a coupling agentselected from the group consisting of diamine, di-epoxy anddi-carboxylic acid compound, provided that at least one of thedi-functional polysiloxanes and the coupling agent contains at least oneepoxy group.

As discussed above, a person skilled in the art will know well how tocovalently attach one or more of monofunctional group terminated PEGs orhydrophilic polymers which are described above to one of the hydroxygroups of a hydroxy-containing chain-extended polysiloxane crosslinkerunder well known coupling reaction conditions as described above ortaught in textbooks.

A chain-extended polysiloxane crosslinker of formula (7) can also beobtained by a process including the steps of: (1) obtaining a bridginglinker having a pendant (linear or 3-arm) hydrophilic polymer chain andtwo first reactive functional groups; (2) reacting the bridging linkerwith at least one di-functional polysiloxane having one solepolysiloxane segment and two terminal second reactive functional groups,in the presence or absence of a coupling agent under coupling reactionconditions, to form an intermediary chain-extended polysiloxane polymerhaving two terminal first or second reactive functional groups, at leasttwo polysiloxane segments, and at least one dangling hydrophilic polymerchain attached to an organic linkage linking a pair of adjacentpolysiloxane segments; and (3) ethylenically functionalizing theintermediary chain-extended polysiloxane polymer by using anethylenically functionalizing vinylic monomer having a third reactivefunctional group (other than ethylenically unsaturated group) capable ofreacting with the first or second reactive functional groups in thepresence or absence of a coupling agent to form a covalent linkage,thereby forming the chain-extended polysiloxane crosslinker of theinvention (i.e., of formula (I)). Preferably, the first reactivefunctional group is selected from the group consisting of amino (—NHR′with R′ as defined above), hydroxyl, carboxyl, and combinations thereof,and the second and third reactive functional groups independent of eachother are selected from the group consisting of hydroxyl groups (—OH),amino groups (—NHR′), carboxyl groups (—COOH), isocyanate groups, epoxygroups, azlactone group, aziridine group, acid chloride, andcombinations thereof.

A bridging linker having a pendant (linear or 3-arm) hydrophilic polymerchain and two first reactive functional groups selected from the groupconsisting of amino, hydroxyl, carboxyl, isocyanate groups, andcombinations thereof by: (a) reacting a mercaptan having one sole thiolgroup and two first reactive functional groups (other than thiol groups)with a mono-ethylenically-functionalized hydrophilic polymer (i.e., alinear or 3-arm hydrophilic polymer having one sole terminal,ethylenically-unsaturated group), under Michael Addition or thiol-enereaction conditions; (b) reacting mono-thiol terminated (linear orY-shape) hydrophilic polymer with a vinylic monomer having two firstreactive functional groups (other than ethylenically unsaturatedgroups), under Michael Addition or thiol-ene reaction conditions; (c)polymerizing a mixture including a chain transfer agent (i.e., amercaptan) having one sole thiol group and at least two first reactivefunctional groups, at least about 60%, preferably at least about 70%,more preferably at least about 80%, even more preferably at least about90%) by weight of one or more hydrophilic vinylic monomers and from 0 toabout 40% (preferably from 0 to about 30%, more preferably from 0 toabout 20%, even more preferably from 0 to about 10%) by weight of one ormore bulky vinylic monomers (any one of those described above); (d)reacting a C₂-C₂₀ compound having three first reactive functional groups(which can be identical to or different from one other) with a (linearor 3-arm) hydrophilic polymer having one sole terminal second reactivefunctional group in the presence or absence of a coupling agent undercoupling reaction conditions, or (e) reacting a C₂-C₂₀ compound havingthree first reactive functional groups (reactive with organic bromide)with a ATRP polymerization product of a polymerizing a mixture includingan organic bromide as ATRP initiator, at least about 60% (preferably atleast about 70%, more preferably at least about 80%, even morepreferably at least about 90%) by weight of one or more hydrophilicvinylic monomers and from 0 to about 40% (preferably from 0 to about30%, more preferably from 0 to about 20%, even more preferably from 0 toabout 10%) by weight of one or more bulky vinylic monomers (any one ofthose described above).

For example, a bridging linker having a pendant hydrophilic polymerchain and two first functional groups can be reacted with a polysiloxanewith two terminal second functional groups, in the presence or absenceof a coupling agent under coupling reaction conditions at a molarequivalent ratio of about 1:2 or higher, to form a di-second functionalgroup-terminated chain extended polysiloxane having two polysiloxanesegments linked through the bridging linker. Such prepared chainextended polysiloxane can be reacted further with a bridging linker at amolar equivalent ratio of about 1:2 to form a new chain-extendedpolysiloxane capped by the bridging linker (i.e., a chain-extendpolysiloxane having two terminal first functional groups and threependant hydrophilic polymer chains and two polysiloxane segments).

As another illustrative example, a chain-extended polysiloxane havingthree polysiloxane segments each pair of which is separated by abridging linker having a pendant hydrophilic polymer chain can beprepared in a one-pot coupling reaction or three step reactions. In aone pot reaction, a bridging linker with two first functional groups anda pendant hydrophilic polymer chain can react with a polysiloxane havingone polysiloxane segment and two terminal second functional groupscoreactive with the first functional group to form covalent linkagesunder coupling reaction conditions at a molar equivalent ratio of about2:3 to form a chain-extended polysiloxane having (a) three polysiloxanesegments each pair of which are linked together through a bridginglinker having a pendant hydrophilic polymer chain and (b) two terminalsecond functional groups. Alternatively, in the first step of three-stepreactions, a bridging linker having a pendant hydrophilic polymer chainand two first functional groups a polysiloxane with two terminal secondfunctional groups can be reacted with a bridging linker having a pendanthydrophilic polymer chain and two first functional groups, in thepresence or absence of a coupling agent under coupling reactionconditions at a molar equivalent ratio of about 2:1 or higher to form apolysiloxane capped (terminated) with one bridging linker at each ends.In the second step, the bridging linker-capped polysiloxane can bereacted with a polysiloxane having two terminal second functional groups(the same as or different from the polysiloxane used in the first step)under coupling reaction conditions at a molar equivalent ratio of about1:2 or higher to form a chain-extended polysiloxane having threepolysiloxane segments, two pendant hydrophilic polymer chains and twoterminal second functional group. Addition step(s) of reactions can beused to add additional polysiloxane segments and/or bridging linkerseach with a pendant hydrophilic polymer chain to a chain-extendedpolysiloxane.

Mono-dihydroxysubstituted-alkyl or alkyloxyalkyl-terminated PEGs areavailable from commercial source (e.g., Ymer™ N120, a lineardifunctional polyethylene glycol monomethyl ether, from Perstorp).Alternatively, a bridging linker having a pendant hydrophilic polymerchain and two first reactive functional groups can be obtained by (a)reacting a mercaptan having one sole thiol group and two first reactivefunctional groups (other than thiol groups) with amono-ethylenically-functionalized hydrophilic polymer (i.e., ahydrophilic polymer having one sole ethylenically unsaturated group), or(b) reacting mono-thiol terminated hydrophilic polymer with a vinylicmonomer having two first reactive functional groups (other thanethylenically unsaturated groups), under Micahel Addition or thiol-enereaction conditions.

In a preferred embodiment, each hydrophilic polymer chain comprises atleast about 60%, preferably at least about 70%, more preferably at leastabout 80%, even more preferably at least about 90%) by weight of one ormore hydrophilic monomers selected from the group consisting ofethyleneglycol, (meth)acrylamide, C₁-C₃ alkyl (meth)acrylamide,di-(C₁-C₃ alkyl) (meth)acrylamide, N-vinylpyrrole,N-vinyl-2-pyrrolidone, 2-vinyloxazoline, 4-vinylpyridine,mono-C₁-C₄alkoxy, mono-(meth)acryloyl terminated polyethyleneglycolhaving a molecular weight of 2000 Daltons or less, di(C₁-C₃ alkylamino)(C₂-C₄ alkyl) (meth)acrylate, N—C₁-C₄alkyl-3-methylene-2-pyrrolidone, N—C₁-C₄alkyl-5-methylene-2-pyrrolidone, N-vinyl C₁-C₆ alkylamide,N-vinyl-N—C₁-C₆ alkyl amide, and combinations thereof. Preferably, thehydrophilic polymer chain comprises a bulky vinylic monomer, which canbe any one of those described above.

Examples of preferred hydrophilic vinylic monomers used in this aspectof the invention are N,N-dimethylacrylamide (DMA),N,N-dimethylmethacrylamide (DMMA), 3-acryloylamino-1-propanol,N-methyl-3-methylene-2-pyrrolidone, N-ethyl-3-methylene-2-pyrrolidone,N-methyl-5-methylene-2-pyrrolidone, N-ethyl-5-methylene-2-pyrrolidone,5-methyl-3-methylene-2-pyrrolidone, 5-ethyl-3-methylene-2-pyrrolidone,1-n-propyl-3-methylene-2-pyrrolidone,1-n-propyl-5-methylene-2-pyrrolidone,1-isopropyl-3-methylene-2-pyrrolidone,1-isopropyl-5-methylene-2-pyrrolidone,1-n-butyl-3-methylene-2-pyrrolidone,1-tert-butyl-3-methylene-2-pyrrolidone, dimethylaminoethyl methacrylate(DMAEMA), N-vinyl-2-pyrrolidone (NVP), a C₁-C₄-alkoxy polyethyleneglycol (meth)acrylate having a weight average molecular weight of up to1500, methacrylic acid, N-vinyl formamide, N-vinyl acetamide, N-vinylisopropylamide, N-vinyl-N-methyl acetamide, N-vinyl caprolactam, andmixtures thereof.

Any mercaptans having 2 to 24 carbon atoms and two reactive functionalgroups selected from the group consisting of amino (—NHR′ with R′ asdefined above), hydroxyl, carboxyl, and combinations thereof can be usedin the invention to prepare a bridging linker. Examples of suchmercaptans include without limitation mercaptoglycerol,2-Mercapto-pyrimidine-4,6-diol; cysteine; 4-amino-5-mercapto-pentanoicacid, 2-mercapto-4-amino-6-hydroxypyrimidine, 2-mercapto-succinic acid,3-mercapto-2-(methylamino)propanoic acid,2-mercapto-4,5-dihydro-1h-imidazole-4,5-diol, 3-mercaptotyramine,mercaptopropanediol, 2-mercaptomethylglutaric acid, 3-mercapto-DL-valinehydrochloride, and combinations thereof.

Any vinylic monomer having two reactive functional groups selected fromthe group consisting of amino (—NHR′ with R′ as defined above),hydroxyl, carboxyl, and combinations thereof can be used in theinvention to prepare a bridging linker having a pendant hydrophilicpolymer chain. Examples of such vinylic monomers include withoutlimitation N,N-2-(meth)acrylamidoglycolic acid, glycerol (meth)acrylate,2-hydroxy-3-aminopropyl (meth)acrylate, 1-hydroxy-2-aminopropyl(meth)acrylate, 1-amino-2-hydroxypropyl (meth)acrylate, glutaconic acid,itaconic acid, citraconic acid, mesaconic acid, maleic acid, fumaricacid, and combinations thereof.

Any linear hydrophilic polymers having one sole thiol or ethylenicallyunsaturated group can be used in the invention to prepare a bridginglinker having a pendant hydrophilic polymer chain. Exemplary hydrophilicpolymers with one ethylenically-unsaturated group or thiol group includewithout limitation mono-ethylenically unsaturated group- ormono-thiol-terminated poly(ethylene glycol) (PEG); mono-ethylenicallyunsaturated group- or mono-thiol-terminatedpolyethyleneglycol/polypropyleneglycol (PEG/PPG) block copolymers;mono-ethylenically unsaturated group- or mono-thiol-terminated polymerscomprising at least about 60% (preferably at least about 70%, morepreferably at least about 80%, even more preferably at least about 90%)by weight of one or more hydrophilic vinylic monomers selected from thegroup consisting of N,N-dialkyl (meth)acrylamide, N-vinylpyrrolidone,N-methyl-N-vinylacetamide, N-vinylacetamide, N-vinyl formamide, N-vinylisopropylamide, di-C₁-C₄ alkylamino-C₂-C₄ alkyl (meth)acrylate,(meth)acrylamide, a C₁-C₄-alkoxy polyethylene glycol (meth)acrylatehaving a weight average molecular weight of up to 200,N-methyl-3-methylene-2-pyrrolidone, 1-methyl-5-methylene-2-pyrrolidone,5-methyl-3-methylene-2-pyrrolidone, or mixture thereof; and combinationsthereof and from 0 to about 40% (preferably from 0 to about 30%, morepreferably from 0 to about 20%, even more preferably from 0 to about10%) by weight of one or more bulky vinylic monomers (any one of thosedescribed above).

Mono-ethylenically unsaturated group- or mono-thiol-terminatedpolyethyleneglycols (PEG's) are available from commercial sources. Amonoethylenically unsaturated group-terminated hydrophilic polymer canbe prepared by ethylenically functionalizing of a hydrophilic polymerhaving one sole reactive functional group selected from the groupconsisting of amino group, hydroxyl group, acid chloride group, carboxylgroup, isocyanate group, anhydride, and epoxy group.

Various monofunctional terminated PEGs can be obtained from commercialsources, e.g., Shearwater Polymers, Inc. and Polymer Sources™. Preferredmonofunctional-terminated PEGs are those PEGs with one amino, hydroxyl,acid chloride, or epoxy group at one terminus and a methoxy or ethoxygroup at the other terminus. Various monofunctionalpolyvinylpyrrolidones (PVPs) with one terminal hydroxy, carboxyl orthiol group can be obtained from commercial sources, e.g., PolymerSources™.

Monofunctional group-terminated linear hydrophilic polymers of one ormore hydrophilic vinylic monomers free of any reactive functional group(other than ethylenically unsaturated group) can be prepared accordingto procedures similar to those described in U.S. Pat. No. 6,218,508,herein incorporated by reference in its entirety. For example, one ormore hydrophilic vinylic monomers without functional group (i.e.,primary amino group, hydroxyl group, isocyanate group, carboxyl group,or epoxy group), a small amount (i.e., about 40% or less, preferablyabout 30% or less, more preferably about 20% or less, even morepreferably about 10% or less by weight, relative to the total amount ofpolymerizable components) of a bulky vinylic monomer, and a chaintransfer agent (e.g., 2-mercaptoethanol, 2-aminoethanethiol,2-mercaptopropinic acid, thioglycolic acid, thiolactic acid, or otherhydroxymercaptanes, aminomercaptans, or carboxyl-containing mercaptanes)are copolymerized (thermally or actinically) in the presence or absenceof an initiator to obtain a monohydroxy-, moncarboxyl-, ormonoamine-terminated hydrophilic polymer or copolymer. Generally, themolar ratio of chain transfer agent to that of one or more hydrophilicvinylic monomers is from about 1:5 to about 1:100. The molar ratio ofchain transfer agent to the hydrophilic vinylic monomer withoutfunctional group is selected to obtain a polymer or copolymer with amolecular weight of from about 500 to about 10,000, preferably fromabout 1000 to about 7,500 Daltons. Mono-epoxy-, mono-isocyanate-, ormono-acid chloride-terminated polymers or copolymers of one or morehydrophilic vinylic monomers can be prepared by covalently attachingepoxy, isocyanate, or acid chloride groups to the above-obtainedmonohydroxy- or monoamine-terminated polymers or copolymers of one ormore hydrophilic vinylic monomers according to any known procedures. Useof monofunctional group-terminated hydrophilic polymers with highermolecular weight may ensure that the interfacial film on a siliconehydrogel material or lens made from a prepolymer of the invention hasadequate thickness and coverage.

Alternatively, monofunctional group-terminated hydrophilic polymers canbe prepared by polymerizing the one or more hydrophilic monomers (freeof reactive functional group other than ethylenically unsaturated group)in the presence of a hydroxyl-, amine-, or carboxyl-containing freeradical initiator at a molar ratio of intiator to the hydrophilicmonomers of from about 1:30 to about 1:700. Examples of initiators withamine, hydroxyl, or carboxy group are azo initiators, such as, e.g.,2,2′-Azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane}dihydrochloride,2,2′-Azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide,2,2′-Azobis[2-methyl-N-(2-hydroxyethyl)propionamide], or 2,2′-Azobis{2-methyl-N-[2-(1-hydroxybutyl)]propionamide},2,2′-Azobis(2-methylpropionamide)dihydrochloride,2,2′-Azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate, orthe likes.

In accordance with the invention, ethylenically functionalizing of amono-functional group-terminated hydrophilic polymer can be carried outby covalently attaching ethylenically unsaturated groups to thefunctional groups (e.g., amine, hydroxyl, carboxyl, isocyanate,anhydride, and/or epoxy groups) of the mono-functional group terminatedhydrophilic polymer by using an ethylenically functionalizing vinylicmonomer (any one of those described above).

Examples of C₂-C₂₀ compounds having three first reactive functionalgroups (which can be identical to or different from one other) includewithout limitation 3-amino-1,2-propanediol, 2-amino-1,3-propanediol,2-amino-2-methylpropane-1,3-diol, α-aminoadipic acid,2,3-dihydroxy-3-methylpentanoic acid, glyceric acid,4-amino-2-hydroxybutanoic acid, 3-amino-2-hydroxypropionic acid,tyrosine, serine, threonine, lysine, aspartate, glutamate,3-hydroxy-3-methylglutaric acid, malic acid, 2-hydroxyglutaric acid,glycerol, diglycerol, 1,1,1-trishydroxymethylethane,1,1,1-trishydroxymethylpropane, 1,2,4-butanetriol, 1,2,6-hexanetriol,erythritol, pentaerythritol, diethylenetriamine,N-2′-aminoethyl-1,3-propylenediamine, N,N-bis(3-aminopropyl)-amine,N,N-bis(6-aminohexyl)amine, triethylenetetramine, the isocyanuratetrimer of hexamethylene diisocyanate, 2,4,6-toluene triisocyanate,p,p′,p″-triphenylmethane triisocyanate, and the trifunctional trimer(isocyanurate) of isophorone diisocyanate, trimesoyl chloride,cyclohexane-1,3,5-tricarbonyl chloride, trimer acid chloride,triglycidylisocyanurate (TGIC), trimethylopropane trimethacrylate,pentaerythritol tetramethacrylate, triallyl isocyanurate, triallylcyanurate, aconitic acid, citric acid, 1,3,5-cyclohexanetricarboxylicacid, 1,3,5-trimethyl-1,3,5-cyclohexanetricarboxylic acid, 1,2,3 benzenetricarboxylic acid, and 1,2,4 benzene tricarboxylic acid. Preferably, aC₂-C₂₀ compound used for preparing a bridging linker having a pendant(linear or 3-arm) hydrophilic polymer chain and two first reactivefunctional groups (i.e., in formula (I) t1 and t2 is zero and L₁, L₂,L₁′ and L₂′ are direct bonds) is 3-amino-1,2-propanediol,2-amino-1,3-propanediol, 2-amino-2-methylpropane-1,3-diol, α-aminoadipicacid, 2,3-dihydroxy-3-methylpentanoic acid, lysine, aspartate, orglutamate. A person skilled in the art understand well how to chose acoupling reaction based on selectivity and/or differential reactivity ofa given functional group. For example, the amine group of3-amino-1,2-propanediol can react with the sole carboxylic group of amonofunctionalized linear or 3-arm hydrophilic polymer in the presenceof a carbodiimide (i.e., 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide(EDC), N,N′-dicyclohexylcarbodiimide (DCC),1-cylcohexyl-3-(2-morpholinoethyl)carbodiimide, diisopropylcarbodiimide) according to well-known carbodiimide-assisted couplingreaction, so as to form a bridging linker with one dangling linear or3-arm hydrophilic polymer chain and two hydroxyl groups.

In accordance with the invention, the three arms of a mono-functional3-arm hydrophilic polymer independent of each other are a linearhydrophilic polymer chain comprising at least about 60%, preferably atleast about 70%, more preferably at least about 80%, even morepreferably at least about 90% by weight of one or more hydrophilicmonomers and they can be identical or different. Each arm is linked to aC₂-C₂₀ compound having three first reactive functional groups selectedfrom the groups consisting of hydroxyl, amino, carboxyl, isocyanategroups, and combination thereof. A monofunctional 3-arm hydrophilicpolymer can be prepared by reacting a first linear hydrophilic polymerhaving one sole terminal second reactive functional group with a C₂-C₂₀compound having three first reactive functional groups to form amono-di(first functional group) terminated linear hydrophilic polymer;reacting a second linear hydrophilic polymer having one sole thirdreactive functional group with the mono-di(first functional group)terminated linear hydrophilic polymer to form an intermediaryhydrophilic polymer composed of the first and send linear hydrophilicpolymers linked by a linkage with one first reactive functional group;and then reacting a third linear hydrophilic polymer having two terminalfourth reactive functional groups with the intermediary hydrophilicpolymer to form a 3-arm hydrophilic polymer having one sole terminalfourth reactive functional group. Preferably, a C₂-C₂₀ compound havingthree first reactive functional groups for preparing a mono-functionalterminated 3-arm hydrophilic polymer comprises three different reactivefunctional groups having different reactivities, for example, such as,4-amino-2-hydroxybutanoic acid, 3-amino-2-hydroxypropionic acid,tyrosine, serine, or threonine.

Alternatively, a bridging linker having a pendant linear hydrophilicpolymer chain and two first reactive functional groups (as describedabove) can be reacting sequentially with one mono-functional terminatedlinear hydrophilic polymer and with a linear hydrophilic polymer havingtwo terminal functional groups under well known coupling reactionconditions, obtain a mono-functional terminated 3-arm hydrophilicpolymer.

A mono-ethylenically unsaturated group terminated 3-arm hydrophilicpolymer can be prepared by covalently attaching ethylenicallyunsaturated groups to the functional group (e.g., amine, hydroxyl,carboxyl, isocyanate, anhydride, and/or epoxy groups) of themono-functional group terminated 3-arm hydrophilic polymer by using anethylenically functionalizing vinylic monomer (as described above).

Any suitable di-functional polysiloxanes can be used to prepare anintermediary chain-extended polysiloxane polymer having two terminalreactive functional groups, at least two polysiloxane segments, and atleast one dangling hydrophilic polymer chain attached to an organiclinkage linking a pair of adjacent polysiloxane segments. Variouspolysiloxanes having two terminal functional groups selected from thegroup consisting of hydroxyl groups (—OH), amino groups (—NHR′),carboxyl groups (—COOH), epoxy groups, isocyanate groups, acidanhydride, and combinations thereof can be obtained from commercialsuppliers (e.g., from Gelest, Inc, or Fluorochem). Otherwise, oneskilled in the art will know how to prepare such difunctionalgroup-terminated polysiloxanes according to procedures known in the artand described in Journal of Polymer Science—Chemistry, 33, 1773 (1995)(herein incorporated by reference in its entirety). Examples ofcommercially available di-functional polysiloxane include withoutlimitation, di-epoxypropoxypropyl-terminated polysiloxane,di-hydroxyethoxypropyl-terminated polysiloxane,di-hydroxyl(polyethylenoxy)propyl-terminated polysiloxane,dicarboxydecyl-terminated polysiloxane, dicarboxypropyl-terminatedpolysiloxane, di-caprolactone terminated polysiloxane,di-N-ethylaminopropyl terminated polysiloxane, di-aminopropyl terminatedpolysiloxane, di-succinic acid anhydride terminated polysiloxane, andcombinations thereof. A person skilled in the art will know well toselect a di-functional polysiloxane and coupling reaction conditions instep (2).

It is understood that the molar equivalent ratio of the bridging linkerhaving one pendant hydrophilic polymer chain to the difunctionalterminated polysiloxane in coupling reaction mixture can determinewhether resultant intermediary chain-extended polysiloxane polymer iscapped with one of the two reactive functional group of the bridginglinker or of the difunctional polysiloxane.

Where the molar equivalent ratio of a first bridging linker to a firstdi-functional terminated polysiloxane is about 2:1 in the couplingreaction mixture, the resultant first intermediary polysiloxane polymerhas one polysiloxane segment and is capped with one of the two reactivefunctional group of the bridging linker. The first intermediary polymerthen can be reacted with a second difunctional polysiloxane (which canbe different from or the same as the first difunctional polysiloxane) ata molar equivalent ratio of 1:2 to form a second intermediarypolysiloxane polymer having three polysiloxane segments and capped withone of the reactive functional groups of the second difunctionalpolysiloxane. Such procedures can be repeated to obtain an intermediarypolymer having a desired number of polysiloxane segments.

Similarly, where the molar equivalent ratio of a first bridging linkerto first difunctional terminated polysiloxane is about 1:2 in thecoupling reaction mixture, the resultant first intermediary polysiloxanepolymer has two polysiloxane segments and is capped with one of the tworeactive functional group of the first difunctional polysiloxane. Theresultant first intermediary chain-extended polysiloxane polymer thencan be ethylenically functionalized to obtain a chain-extendedpolysiloxane crosslinker (i.e., step (3)) of the invention or reactedwith a second bridging linker (which can be different from or the sameas the first bridging linker) at a molar equivalent ratio of 1:2 to forma second intermediary polysiloxane polymer having the same twopolysiloxane segments but capped with one of the reactive functionalgroups of the second bridging linker. The second intermediarypolysiloxane can further be reacted with a second difunctionalpolysiloxane (which can be different from or the same as the firstdifunctional polysiloxanes) to form a third intermediary polysiloxanepolymer having four polysiloxane segments and capped with one of thereactive functional groups of the second difunctional polysiloxane. Suchprocedures can be repeated to obtain an intermediary polymer having adesired number of polysiloxane segments.

It is understood that two or three bridging linkers can be covalentlylinked together, in a coupling reaction (any one described above), toform a new bridging linker having two or more pendant hydrophilicpolymer chains (i.e., corresponding the formula (I) in which v1 and ω1independent of each other are an integer of 2 or 3).

An intermediary chain-extended polysiloxane polymer obtained then can beethylenically functionalized to obtain a chain-extended polysiloxanecrosslinker of the invention, according to any ethylenicallyfunctionalizing procedures described above and using any ethylenicallyfunctionalizing vinylic monomer described above. Preferably, covalentlinkages formed in the ethylenically functionalizing process arelinkages free of ester linkages between one carbon-carbon double bondand one polydisiloxane segment. For example, where the terminalfunctional groups of an intermediary chain-extended polysiloxane polymeris amino or hydroxyl group, an azlactone-containing vinylic monomer oran isocyanate-containing (meth)acrylamide monomer (which can be forexample the 1:1 reaction product of C₂-C₄ hydroxyalkyl (meth)acrylamide(e.g., hydroxyethyl (meth)acrylamide) with a hexamethyl-1,6-diisocyanate(or isophorene diisocyanate or any diisocyanate described above)) can beused as ethylenically functionalizing vinylic monomer; wherein theterminal functional groups of an intermediary chain-extendedpolysiloxane polymer are an amino group, a (meth)acrylic acid chloridecan be as ethylenically functionalizing vinylic monomer; where theterminal functional groups of an intermediary chain-extendedpolysiloxane polymer are a 1,2- or 1,3-diol, acrylamidoacetaldehydedimethylacetal (or methacrylamidoacetaldehyde dimethylacetal) can beused as ethylenically functionalizing vinylic monomer.

In accordance with the invention, a hydrophilized polysiloxane orchain-extended polysiloxane crosslinker of formula (8) can be obtainedby a process including the steps of: (1) reacting a bridging linkerhaving a pendant hydrophilic polymer chain (any one of those describedabove) with at least one polysiloxane mono-terminated with one organicmoiety having two reactive functional group, e.g.,mono-dicarbinol-terminated polysiloxane having one sole polysiloxanesegment (i.e., a mono-bishydroxyalkyl-terminated ormono-bishydroxyalkyloxyalkyl-terminated polysiloxane), in the presenceor absence of a coupling agent under coupling reaction conditions, toform a comb-like compound having (a) at least one pendant polysiloxanechain (i.e., a segment terminated with no reactive functional group),(b) at least one pendant hydrophilic polymer chain and (c) two terminalfirst reactive functional groups; and (2) ethylenically functionalizingthe comb-like compound by using an ethylenically functionalizing vinylicmonomer having a second reactive functional group (other thanethylenically unsaturated group) capable of reacting with the firstreactive functional groups in the presence or absence of a couplingagent to form a covalent linkage, thereby forming a hydrophilizedpolysiloxane crosslinker of formula (10).

A mono-dicarbinol polysiloxane can be obtained from commercial sources,such as Shin Etsu, Gelest, Inc.

A polysiloxane mono-terminated with one organic moiety having tworeactive functional groups can be obtained by (a) reacting a mercaptanhaving one sole thiol group and two first reactive functional groups(other than thiol groups) with a mono-vinyl-, mono-acryloyl-,mono-methacryloyl-, or mono-allyl-terminated polysiloxane, or (b)reacting mono-thiol terminated polysiloxane with a vinylic monomerhaving two first reactive functional groups (other than ethylenicallyunsaturated groups), under Micahel Addition or thiol-ene reactionconditions.

Mono-vinyl-, mono-acryloyl-, mono-methacryloyl-, andmono-allyl-terminated polysiloxanes can be obtained from commercialsources (e.g., from Shin Etsu, Gelest, Inc, or Fluorochem).Alternatively, they can be obtained by ethylenically functionalizing amono-functional polysiloxane obtained from a commercial source.

Above described mercaptans having 2 to 24 carbon atoms and two reactivefunctional group selected from the group consisting of amino (—NHR′ withR′ as defined above), hydroxyl, carboxyl, and combinations thereof canbe used in the invention to prepare a polysiloxane terminated withmono-organic moiety having two reactive functional groups. Examples ofsuch mercaptans include without limitation mercaptoglycerol,2-Mercapto-pyrimidine-4,6-diol; 4-amino-5-mercapto-pentanoic acid,2-mercapto-4-amino-6-hydroxypyrimidine, 2-mercapto-succinic acid,3-mercapto-2-(methylamino)propanoic acid, 2-mercapto-4,5-dihydro-1h-imidazole-4,5-diol, 3-mercaptotyramine, mercaptopropanediol,2-mercaptomethylglutaric acid, 3-mercapto-DL-valine hydrochloride, andcombinations thereof.

Any vinylic monomer having two reactive functional groups selected fromthe group consisting of amino (—NHR′ with R′ as defined above),hydroxyl, carboxyl, and combinations thereof can be used in theinvention to prepare a bridging linker having a pendant hydrophilicpolymer chain in step (2). Examples of such vinylic monomers includewithout limitation N,N-2-(meth)acrylamidoglycolic acid, glycerol(meth)acrylate, 2-hydroxy-3-aminopropyl (meth)acrylate,1-hydroxy-2-aminopropyl (meth)acrylate, 1-amino-2-hydroxypropyl(meth)acrylate, glutaconic acid, itaconic acid, citraconic acid,mesaconic acid, maleic acid, fumaric acid, and combinations thereof.

In accordance with the invention, any suitable hydrophilic vinylicmonomers can be used in preparation of a prepolymer of the invention.Suitable hydrophilic vinylic monomers are, without this being anexhaustive list, hydroxyl-substituted C₁-C₆ alkyl (meth)acrylates,hydroxyl-substituted C₁-C₆ alkyl vinyl ethers, C₁ to C₆ alkyl(meth)acrylamide, di-(C₁-C₆ alkyl) (meth)acrylamide, N-vinylpyrrole,N-vinyl-2-pyrrolidone, 2-vinyloxazoline,2-vinyl-4,4′-dialkyloxazolin-5-one, 2- and 4-vinylpyridine, olefinicallyunsaturated carboxylic acids having a total of 3 to 6 carbon atoms,amino-substituted C₁-C₆ alkyl- (where the term “amino” also includesquaternary ammonium), mono(C₁-C₆ alkyl amino)(C₁-C₆ alkyl) and di(C₁-C₆alkyl amino)(C₁-C₆ alkyl) (meth)acrylates, allyl alcohol, N-vinyl C₁-C₆alkylamide, N-vinyl-N—C₁-C₆ alkyl amide, and combinations thereof.

Examples of preferred hydrophilic vinylic monomers free of reactivefunctional group are N,N-dimethylacrylamide (DMA),N-methyl-3-methylene-2-pyrrolidone, 1-ethyl-3-methylene-2-pyrrolidone,1-methyl-5-methylene-2-pyrrolidone, 1-ethyl-5-methylene-2-pyrrolidone,5-methyl-3-methylene-2-pyrrolidone, 5-ethyl-3-methylene-2-pyrrolidone,1-n-propyl-3-methylene-2-pyrrolidone,1-n-propyl-5-methylene-2-pyrrolidone,1-isopropyl-3-methylene-2-pyrrolidone,1-isopropyl-5-methylene-2-pyrrolidone,1-n-butyl-3-methylene-2-pyrrolidone,1-tert-butyl-3-methylene-2-pyrrolidone, N-vinyl-2-pyrrolidone (NVP),vinylpyridine, a C₁-C₄-alkoxy polyethylene glycol (meth)acrylate havinga weight average molecular weight of up to 1500, N-vinyl formamide,N-vinyl acetamide, N-vinyl isopropylamide, N-vinyl-N-methyl acetamide,N-vinyl caprolactam, and mixtures thereof. Examples of the mostpreferred hydrophilic vinylic monomers include without limitationN-vinylpyrrolidone, N,N-dimethyl (meth)acrylamide, (meth)acrylamide,N-vinyl formamide, N-vinyl acetamide, N-vinyl isopropylamide,N-vinyl-N-methyl acetamide, N-methyl-3-methylene-2-pyrrolidone,1-ethyl-3-methylene-2-pyrrolidone, 1-methyl-5-methylene-2-pyrrolidone,1-ethyl-5-methylene-2-pyrrolidone, 5-methyl-3-methylene-2-pyrrolidone,5-ethyl-3-methylene-2-pyrrolidone, and combinations thereof.

In accordance with the invention, the polymerizable units are free ofany polysiloxane segment and each comprise a basic monomeric unit beinga part of a polymer chain of the prepolymer and a pendant or terminal,ethylenically-unsaturated group attached thereon, wherein each basicmonomeric unit is derived from a first ethylenically functionalizingvinylic monomer having a first reactive functional group, wherein thependant or terminal ethylenically unsaturated group is derived from asecond ethylenically functionalizing vinylic monomer having a secondreactive functional group which reacts with one first reactivefunctional in the presence or absence of a crosslinking agent to form acovalent linkage. The first and second reactive functional groups areselected from the group consisting of amino group, hydroxyl group,carboxyl group, azlactone group, isocyanate group, epoxy group,aziridine group, acid chloride, and combination thereof. Examples ofsuch vinylic monomers are those ethylenically functionalizing vinylicmonomers described above. Preferably, the first ethylenicallyfunctionalizing vinylic monomer is selected from the group consisting ofhydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyethyl(meth)acrylamide, hydroxypropyl (meth)acrylamide, allyl alcohol,aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, aminoethyl(meth)acrylamide, aminopropyl (meth)acrylamide, allyl amine,(meth)acrylic acid, ethylacrylic acid, propylacrylic acid, butylacrylicacid, glycidyl (meth)acrylate, vinyl glycidyl ether, allyl glycidylether, isocynatoethyl (meth)acrylate, 2-(1-aziridinyl) ethyl(meth)acrylate, 3-(1-aziridinyl) propyl (meth)acrylate, 4-(1-aziridinyl)butyl (meth)acrylate, 2-vinyl-4,4-dimethyl-1,3-oxazolin-5-one (VDMO),2-isopropenyl-4,4-dimethyl-1,3-oxazolin-5-one (IPDMO), and combinationthereof. Most preferably, the first ethylenically functionalizingvinylic monomer is selected from the group consisting of hydroxyethyl(meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyethyl(meth)acrylamide, hydroxypropyl (meth)acrylamide, allyl alcohol,aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, aminoethyl(meth)acrylamide, aminopropyl (meth)acrylamide, allyl amine, andcombinations thereof.

In accordance with the invention, the content of the polymerizable unitsare determined based on weight percentage of the ethylenicallyfunctionalizing vinylic monomer present in the polymerizable compositionfor making an water-processable intermediary copolymer relative to thetotal weight of polymerizable components in the polymerizablecomposition or the weight percentage of the ethylenicallyfunctionalizing vinylic monomer used in ethylenically functionalizingthe intermediary copolymer to form the prepolymer of the invention,relative to the weight of the prepolymer.

A chain transfer agent (containing at least one thiol group) is used tocontrol the molecular weight of the resultant intermediary copolymer.Where a chain transfer has a reactive functional group such as amine,hydroxyl, carboxyl, epoxy, isocyanate, azlactone, or aziridine group, itcan provide terminal or pendant functionality (amine, hydroxyl,carboxyl, epoxy, isocyanate, azlactone, or aziridine group) forsubsequent ethylenical functionalization of the resultant intermediarycopolymer.

Any suitable hydrophobic vinylic monomers can be used in the preparationof a water-processable prepolymer of the invention. Examples ofpreferred hydrophobic vinylic monomers include methyl (meth)acrylate,ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate,butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate,t-butyl (meth)acrylate, cyclohexylacrylate, 2-ethylhexylacrylate, vinylacetate, vinyl propionate, vinyl butyrate, vinyl valerate, styrene,chloroprene, vinyl chloride, vinylidene chloride, acrylonitrile,1-butene, butadiene, methacrylonitrile, vinyl toluene, vinyl ethylether, perfluorohexylethyl-thio-carbonyl-aminoethyl-methacrylate,isobornyl methacrylate, trifluoroethyl methacrylate,hexafluoro-isopropyl methacrylate, hexafluorobutyl methacrylate, asilicone-containing vinylic monomer, and mixtures thereof.

In a preferred embodiment, the polymerizable composition comprises apolymerizable UV-absorbing agent. Preferred polymerizable UV absorbingagents include without limitation2-(2-hydroxy-5-vinylphenyl)-2H-benzotriazole,2-(2-hydroxy-5-acrylyloxyphenyl)-2H-benzotriazole,2-(2-hydroxy-3-methacrylamido methyl-5-tert octylphenyl)benzotriazole,2-(2′-hydroxy-5′-methacrylamidophenyl)-5-chlorobenzotriazole,2-(2′-hydroxy-5′-methacrylamidophenyl)-5-methoxybenzotriazole,2-(2′-hydroxy-5′-methacryloxypropyl-3′-t-butyl-phenyl)-5-chlorobenzotriazole,2-(2′-hydroxy-5′-methacryloxyethylphenyl)benzotriazole,2-(2′-hydroxy-5′-methacryloxypropylphenyl)benzotriazole,2-hydroxy-4-acryloxy alkoxy benzophenone, 2-hydroxy-4-methacryloxyalkoxy benzophenone, allyl-2-hydroxybenzophenone,2-hydroxy-4-methacryloxy benzophenone. A polymerizable UV-absorbingagent is generally is present in the polymerizable composition forpreparing a water-processable prepolymer of the invention in an amountsufficient to render a contact lens, which is made from a lens formingmaterial including the prepolymer and which absorbs at least about 80percent of the UV light in the range of from about 280 nm to about 370nm that impinges on the lens. A person skilled in the art willunderstand that the specific amount of UV-absorbing agent used in thepolymerizable composition will depend on the molecular weight of theUV-absorbing agent and its extinction coefficient in the range fromabout 280 to about 370 nm. In accordance with the invention, thepolymerizable composition comprises about 0.2% to about 5.0%, preferablyabout 0.3% to about 2.5%, more preferably about 0.5% to about 1.8%, byweight of a UV-absorbing agent.

In accordance with the invention, ethylenically functionalizing of anintermediary copolymer can be carried out by covalently attachingethylenically unsaturated groups to the functional groups (e.g., amine,hydroxyl, carboxyl, isocyanate, and/or epoxy groups) of the intermediarycopolymer. Any vinylic monomer having a hydroxy, amino, carboxyl, epoxy,aziridine, acid-chloride, isocyanate group, which is coreactive withisocyanate, amine, hydroxyl, carboxy, epoxy, aziridine, or azlactonegroups of an intermediary copolymer in the absence or presence of acoupling agent (those described above), can be used in ethylenicallyfunctionalizing the polysiloxane. Any ethylenically-functionalizingvinylic monomers described above can be used in the ethylenicalfunctionalization of an intermediary copolymer to make a prepolymer ofthe invention.

The polymerizable composition for preparing an intermediary copolymercan be a melt, a solventless liquid in which all necessary componentsare blended together, or a solution in which all necessary component isdissolved in an inert solvent (i.e., should not interfer with thereaction between the reactants in the mixture), such as water, anorganic solvent, or mixture thereof, as known to a person skilled in theart.

Example of suitable solvents includes without limitation, water,tetrahydrofuran, tripropylene glycol methyl ether, dipropylene glycolmethyl ether, ethylene glycol n-butyl ether, ketones (e.g., acetone,methyl ethyl ketone, etc.), diethylene glycol n-butyl ether, diethyleneglycol methyl ether, ethylene glycol phenyl ether, propylene glycolmethyl ether, propylene glycol methyl ether acetate, dipropylene glycolmethyl ether acetate, propylene glycol n-propyl ether, dipropyleneglycol n-propyl ether, tripropylene glycol n-butyl ether, propyleneglycol n-butyl ether, dipropylene glycol n-butyl ether, tripropyleneglycol n-butyl ether, propylene glycol phenyl ether dipropylene glycoldimetyl ether, polyethylene glycols, polypropylene glycols, ethylacetate, butyl acetate, amyl acetate, methyl lactate, ethyl lactate,i-propyl lactate, methylene chloride, 2-butanol, 1-propanol, 2-propanol,menthol, cyclohexanol, cyclopentanol and exonorborneol, 2-pentanol,3-pentanol, 2-hexanol, 3-hexanol, 3-methyl-2-butanol, 2-heptanol,2-octanol, 2-nonanol, 2-decanol, 3-octanol, norborneol, tert-butanol,tert-amyl, alcohol, 2-methyl-2-pentanol, 2,3-dimethyl-2-butanol,3-methyl-3-pentanol, 1-methylcyclohexanol, 2-methyl-2-hexanol,3,7-dimethyl-3-octanol, 1-chloro-2-methyl-2-propanol,2-methyl-2-heptanol, 2-methyl-2-octanol, 2-2-methyl-2-nonanol,2-methyl-2-decanol, 3-methyl-3-hexanol, 3-methyl-3-heptanol,4-methyl-4-heptanol, 3-methyl-3-octanol, 4-methyl-4-octanol,3-methyl-3-nonanol, 4-methyl-4-nonanol, 3-methyl-3-octanol,3-ethyl-3-hexanol, 3-methyl-3-heptanol, 4-ethyl-4-heptanol,4-propyl-4-heptanol, 4-isopropyl-4-heptanol, 2,4-dimethyl-2-pentanol,1-methylcyclopentanol, 1-ethylcyclopentanol, 1-ethylcyclopentanol,3-hydroxy-3-methyl-1-butene, 4-hydroxy-4-methyl-1-cyclopentanol,2-phenyl-2-propanol, 2-methoxy-2-methyl-2-propanol2,3,4-trimethyl-3-pentanol, 3,7-dimethyl-3-octanol, 2-phenyl-2-butanol,2-methyl-1-phenyl-2-propanol and 3-ethyl-3-pentanol,1-ethoxy-2-propanol, 1-methyl-2-propanol, t-amyl alcohol, isopropanol,1-methyl-2-pyrrolidone, N,N-dimethylpropionamide, dimethyl formamide,dimethyl acetamide, dimethyl propionamide, N-methyl pyrrolidinone, andmixtures thereof.

The copolymerization of a polymerizable composition for preparing anintermediary copolymer may be induced photochemically or preferablythermally. Suitable thermal polymerization initiators are known to theskilled artisan and comprise, for example peroxides, hydroperoxides,azo-bis(alkyl- or cycloalkylnitriles), persulfates, percarbonates ormixtures thereof. Examples are benzoylperoxide, tert.-butyl peroxide,di-tert.-butyl-diperoxyphthalate, tert.-butyl hydroperoxide,azo-bis(isobutyronitrile) (AIBN), 1,1-azodiisobutyramidine, 1,1′-azo-bis(1-cyclohexanecarbonitrile), 2,2′-azo-bis(2,4-dimethylvaleronitrile) andthe like. The polymerization is carried out conveniently in anabove-mentioned solvent at elevated temperature, for example at atemperature of from 25 to 100° C. and preferably 40 to 80° C. Thereaction time may vary within wide limits, but is conveniently, forexample, from 1 to 24 hours or preferably from 2 to 12 hours. It isadvantageous to previously degas the components and solvents used in thepolymerization reaction and to carry out said copolymerization reactionunder an inert atmosphere, for example under a nitrogen or argonatmosphere. Copolymerization can yield optical clear well-definedcopolymers which may be worked up in conventional manner using forexample extraction, precipitation, ultrafiltration and the liketechniques.

In accordance with the invention, a water-processable prepolymer of theinvention comprises from about 20% to about 50%, preferably from about25% to about 45%, more preferably from about 28% to about 40%, by weightof silicone relative to the total weight of the prepolymer. As used inthis patent application, the term “silicone” refers to a tris(organicgroup)-substituted silyl group and/or a di(organic group)-substitutedsiloxane unit, wherein the organic group can be alkyl,tris(methyl)siloxyl, and/or alkene diradical. The weight percentage ofsilicone in a prepolymer can be calculated based on the percentages ofall of the siloxane-containing vinylic monomer(s) and hydrophilizedpolysiloxane and/or chain-extended polysiloxane crosslinker(s) relativeto the total weight of all of polymerizable components and based on theweight percentages of silicone relative to the molecular weight (oraverage molecular weight) of the siloxane-containing vinylic monomer(s)and hydrophilized polysiloxane and/or chain-extended polysiloxanecrosslinker(s). For example, for a polymerizable composition for makingan intermediary copolymer comprising, as polymerizable components, about35% by weight of MA-PDMS100-PEG750 (made of isocyantoethylmethacrylate(IEM), α,ω-bishydroxyethoxypropyl-terminated polydimethylsiloxane(PDMS1000, m.w.˜1000, X-22-160AS from ShinEtsu), isophorone diisocyanate(IPDI), and mono-methoxy terminated polyethylene glycol (PEG750,m.w.˜750), i.e., IEM-PDMS1000-IPDI-PEG750 see formula below forstructural information), about 20% by weight of Hydroxy-4 (see formulabelow for structural information) and about 45% by weight of DMA(N,N-dimethyl acrylamide), the weight percentage of silicone in theintermediary copolymer can be calculated as follows.

The percentage of silicone in MA-PDMS1000-PEG750 can be calculated to be

${{{Silicone}\mspace{14mu}\%\mspace{14mu}\left( {w\text{/}w} \right)} \approx {\frac{M_{{PDMS}\; 1000}}{M_{IEM} + M_{{PDMS}\; 1000} + M_{IPDI} + M_{{PEG}\; 750}} \times 100}} = {\frac{1000}{155 + 1000 + 222 + 750} = {47{\%.}}}$The percentage of silicone in Hydroxy-4 can be calculated to be about71% (equal to the weight of the moiety in the dashed box divided by themolecular weight of Hydroxy-4). The percentage of silicone in thecopolymer obtained from the polymerizable composition can be calculatedto be

$\begin{matrix}{{{Silicone}\mspace{14mu}\%\left( {w\text{/}w} \right)} = {\left\lbrack {{Silicone}\mspace{14mu}\%} \right\rbrack_{{MA} - {{PDMS}\; 1000} - {{PEG}\; 750}} \times}} \\{\left\lbrack {{MA}\text{-}{PDMS}\; 1000\text{-}{PEG}\; 750} \right\rbrack +} \\{\left\lbrack {{Silicone}\mspace{14mu}\%} \right\rbrack_{{Hydroxy} - 4} \times \left\lbrack {{Hydroxy}\text{-}4} \right\rbrack} \\{= {{{47\% \times 35\%} + {63\% \times 20\%}} = {30.7\%}}}\end{matrix}$

In accordance with the invention, a water-processable prepolymer of theinvention has a high water solubility or dispersibility of at leastabout 5%, preferably at least about 10%, more preferably at least about20% by weight in water. The prepolymer is capable of being actinicallycrosslinked, in the absence of one or more vinylic monomers, to form asilicone hydrogel contact lens having a water content of from about 20%to about 75% (preferably from about 25% to about 70%, more preferablyfrom about 30% to about 65%) by weight when fully hydrated, an oxygenpermeability (Dk) of at least about 40 barrers (preferably at leastabout 50 barrers, more preferably at least about 60 barrers, and evenmore preferably at least about 70 barrers), and optionally (butpreferably) a hydrophilic surface characterized by an average watercontact angle of about 90 degrees or less (preferably about 80 degreesor less, more preferably 70 degrees or less, even more preferably about60 degrees or less) without post molding surface treatment.

A water-processable prepolymer of the invention can find particular usein preparing silicone hydrogel ophthalmic lenses, in particular contactlenses.

It should be understood that although various preferred embodiments ofthe invention may be separately described above, they can be combined inany desirable fashion to arrive at different preferred embodiments ofthe invention.

In another aspect, the invention provides a soft contact lens. The softcontact lens of the invention comprises: a silicone hydrogel materialthat is obtained by curing a lens-forming material in a mold, whereinthe lens-forming formulation (or material) comprises a water-processableprepolymer of the invention (as described above in detail) and one ormore components selected from the group consisting of a hydrophilicvinylic monomer, a hydrophobic vinylic monomer, a crosslinking agenthaving a molecular weight of less than 700 Daltons, a polymerizableUV-absorbing agent, a visibility tinting agent (e.g., dyes, pigments, ormixtures thereof), antimicrobial agents (e.g., preferably silvernanoparticles), a bioactive agent, leachable lubricants, leachabletear-stabilizing agents, and mixtures thereof, wherein the siliconehydrogel contact lens has a water content of from about 20% to about 75%(preferably from about 25% to about 70%, more preferably from about 30%to about 65%) by weight when fully hydrated, an oxygen permeability (Dk)of at least about 40 barrers (preferably at least about 50 barrers, morepreferably at least about 60 barrers, and even more preferably at leastabout 70 barrers), and optionally (but preferably) a hydrophilic surfacecharacterized by an average water contact angle of about 90 degrees orless (preferably about 80 degrees or less, more preferably 70 degrees orless, even more preferably about 60 degrees or less) without postmolding surface treatment.

In accordance with the invention, a lens-forming formulation (ormaterial) is a fluid composition, which can be a solution or a melt at atemperature from about 20° C. to about 85° C. Preferably, a lens-formingmaterial is a solution of at least one prepolymer of the invention andother desirable components in an ophthalmically compatible solvent(e.g., water, 1,2-propylene glycol, a polyethyleneglycol having amolecular weight of about 400 Daltons or less, or a mixture thereof).

Various embodiments of water-processable prepolymers, hydrophilicvinylic monomers, hydrophobic vinylic monomers, solvents, crosslinkingagents, polymerizable UV-absorbing agents, photoinitiators are describedabove and can be used in this aspect of the invention.

Examples of cross-linking agents include without limitationtetraethyleneglycol di-(meth)acrylate, triethyleneglycoldi-(meth)acrylate, ethyleneglycol di-(meth)acrylate, diethyleneglycoldi-(meth)acrylate, bisphenol A dimethacrylate, vinyl methacrylate,ethylenediamine di(meth)acrylamide, glycerol dimethacrylate,allyl(meth)acrylate, N,N′-methylenebis(meth)acrylamide,N,N′-ethylenebis(meth)acrylamide, N,N′-dihydroxyethylenebis(meth)acrylamide,1,3-bis(methacrylamidopropyl)-1,1,3,3-tetrakis(trimethylsiloxy)disiloxane,1,3-bis(N-(meth)acrylamidopropyl)-1,1,3,3-tetrakis-(trimethylsiloxy)disiloxane,1,3-bis(methacrylamidobutyl)-1,1,3,3-tetrakis(trimethylsiloxy)-disiloxane,1,3-bis(methacryloxyethylureidopropyl)-1,1,3,3-tetrakis(trimethylsiloxy)disiloxane,a product of diamine (preferably selected from the group consisting ofN,N′-bis(hydroxyethyl)ethylenediamine, N,N′-dimethylethylenediamine,ethylenediamine, N,N′-dimethyl-1,3-propanediamine,N,N′-diethyl-1,3-propanediamine, propane-1,3-diamine,butane-1,4-diamine, pentane-1,5-diamine, hexamethylenediamine,isophorone diamine, and combinations thereof) and epoxy-containingvinylic monomer (preferably selected from the group consisting ofglycidyl (meth)acrylate, vinyl glycidyl ether, allyl glycidyl ether, andcombinations thereof), combinations thereof. A more preferredcross-linking agent to be used in the preparation of a prepolymer of theinvention is tetra(ethyleneglycol) diacrylate, tri(ethyleneglycol)diacrylate, ethyleneglycol diacrylate, di(ethyleneglycol) diacrylate,glycerol dimethacrylate, allyl(meth)acrylate, N,N′-methylenebis(meth)acrylamide, N,N′-ethylene bis(meth)acrylamide,N,N′-dihydroxyethylene bis(meth)acrylamide, or combination thereof.

The bioactive agent incorporated in the polymeric matrix is any compoundthat can prevent a malady in the eye or reduce the symptoms of an eyemalady. The bioactive agent can be a drug, an amino acid (e.g., taurine,glycine, etc.), a polypeptide, a protein, a nucleic acid, or anycombination thereof. Examples of drugs useful herein include, but arenot limited to, rebamipide, ketotifen, olaptidine, cromoglycolate,cyclosporine, nedocromil, levocabastine, lodoxamide, ketotifen, or thepharmaceutically acceptable salt or ester thereof. Other examples ofbioactive agents include 2-pyrrolidone-5-carboxylic acid (PCA), alphahydroxyl acids (e.g., glycolic, lactic, malic, tartaric, mandelic andcitric acids and salts thereof, etc.), linoleic and gamma linoleicacids, and vitamins (e.g., B5, A, B6, etc.).

Examples of leachable lubricants include without limitation mucin-likematerials (e.g., polyglycolic acid) and non-crosslinkable hydrophilicpolymers (i.e., without ethylenically unsaturated groups).

Any hydrophilic polymers without any ethylenically unsaturated groupscan be used as leachable lubricants. Preferred examples ofnon-crosslinkable hydrophilic polymers include, but are not limited to,polyvinyl alcohols (PVAs), polyamides, polyimides, polylactone, ahomopolymer of a vinyl lactam, a copolymer of at least one vinyl lactamin the presence or in the absence of one or more hydrophilic vinyliccomonomers, a homopolymer of acrylamide or methacrylamide, a copolymerof acrylamide or methacrylamide with one or more hydrophilic vinylicmonomers, polyethylene oxide (i.e., polyethylene glycol (PEG)), apolyoxyethylene derivative, poly-N—N-dimethylacrylamide, polyacrylicacid, poly 2 ethyl oxazoline, heparin polysaccharides, polysaccharides,and mixtures thereof.

The weight-average molecular weight M_(w) of the non-crosslinkablehydrophilic polymer is preferably from 5,000 to 500,000, more preferablyfrom 10,000 to 300,000, even more preferably from 20,000 to 100,000.

Examples of leachable tear-stabilizing agents include, withoutlimitation, phospholipids, monoglycerides, diglycerides, triglycerides,glycolipids, glyceroglycolipids, sphingolipids, sphingo-glycolipids,fatty alcohols, fatty acids, mineral oils, and mixtures thereof.Preferably, a tear stabilizing agent is a phospholipid, a monoglyceride,a diglyceride, a triglyceride, a glycolipid, a glyceroglycolipid, asphingolipid, a sphingo-glycolipid, a fatty acid having 8 to 36 carbonatoms, a fatty alcohol having 8 to 36 carbon atoms, or a mixturethereof.

Lens molds for making contact lenses are well known to a person skilledin the art and, for example, are employed in cast molding or spincasting. For example, a mold (for cast molding) generally comprises atleast two mold sections (or portions) or mold halves, i.e. first andsecond mold halves. The first mold half defines a first molding (oroptical) surface and the second mold half defines a second molding (oroptical) surface. The first and second mold halves are configured toreceive each other such that a lens forming cavity is formed between thefirst molding surface and the second molding surface. The moldingsurface of a mold half is the cavity-forming surface of the mold and indirect contact with lens-forming material.

Methods of manufacturing mold sections for cast-molding a contact lensare generally well known to those of ordinary skill in the art. Theprocess of the present invention is not limited to any particular methodof forming a mold. In fact, any method of forming a mold can be used inthe present invention. The first and second mold halves can be formedthrough various techniques, such as injection molding or lathing.Examples of suitable processes for forming the mold halves are disclosedin U.S. Pat. No. 4,444,711 to Schad; U.S. Pat. No. 4,460,534 to Boehm etal.; U.S. Pat. No. 5,843,346 to Morrill; and U.S. Pat. No. 5,894,002 toBoneberger et al., which are also incorporated herein by reference.

Virtually all materials known in the art for making molds can be used tomake molds for making contact lenses. For example, polymeric materials,such as polyethylene, polypropylene, polystyrene, PMMA, Topas® COC grade8007-S10 (clear amorphous copolymer of ethylene and norbornene, fromTicona GmbH of Frankfurt, Germany and Summit, N.J.), or the like can beused. Other materials that allow UV light transmission could be used,such as quartz glass and sapphire.

In a preferred embodiment, reusable molds are used and the lens-formingcomposition is cured (i.e., polymerized) actinically under a spatiallimitation of actinic radiation to form a silicone hydrogel contactlens. Examples of preferred reusable molds are those disclosed in U.S.patent application Ser. No. 08/274,942 filed Jul. 14, 1994, Ser. No.10/732,566 filed Dec. 10, 2003, Ser. No. 10/721,913 filed Nov. 25, 2003,and U.S. Pat. No. 6,627,124, which are incorporated by reference intheir entireties. Reusable molds can be made of quartz, glass, sapphire,CaF₂, a cyclic olefin copolymer (such as for example, Topas® COC grade8007-S10 (clear amorphous copolymer of ethylene and norbornene) fromTicona GmbH of Frankfurt, Germany and Summit, N.J., Zeonex® and Zeonor®from Zeon Chemicals LP, Louisville, Ky.), polymethylmethacrylate (PMMA),polyoxymethylene from DuPont (Delrin), Ultem® (polyetherimide) from G.E.Plastics, PrimoSpire®, etc.

In accordance with the invention, the lens-forming formulation (orcomposition) can be introduced (dispensed) into a cavity formed by amold according to any known methods.

After the lens-forming composition is dispensed into the mold, it ispolymerized to produce a contact lens. Crosslinking may be initiatedthermally or actinically, preferably by exposing the lens-formingcomposition in the mold to a spatial limitation of actinic radiation tocrosslink the polymerizable components in the lens-forming composition.

Where the lens-forming composition comprises a polymerizableUV-absorbing agent (i.e., a UV-absorbing moiety-containing vinylicmonomer), a benzoylphosphine oxide photoinitiator is preferably used asthe photoinitiator in the invention. Preferred benzoylphosphine oxidephotoinitiators include without limitation2,4,6-trimethylbenzoyldiphenylophosphine oxide;bis-(2,6-dichlorobenzoyl)-4-N-propylphenylphosphine oxide; andbis-(2,6-dichlorobenzoyl)-4-N-butylphenylphosphine oxide. It isunderstood that any photoinitiators other than benzoylphosphine oxideinitiators can be used in the invention.

Opening of the mold so that the molded article can be removed from themold may take place in a manner known per se.

The molded contact lens can be subject to lens extraction to removeunpolymerized polymerizable components. The extraction solvent can beany solvent known to a person skilled in the art. Examples of suitableextraction solvent are those described above. Preferably, water or anaqueous solution is used as extraction solvent. After extraction, lensescan be hydrated in water or an aqueous solution of a wetting agent(e.g., a hydrophilic polymer).

The molded contact lenses can further subject to further processes, suchas, for example, packaging in lens packages with a packaging solutionwhich can contain about 0.005% to about 5% by weight of a wetting agent(e.g., a hydrophilic polymer described above or the like known to aperson skilled in the art) and/or a viscosity-enhancing agent (e.g.,methyl cellulose (MC), ethyl cellulose, hydroxymethylcellulose,hydroxyethyl cellulose (HEC), hydroxypropylcellulose (HPC),hydroxypropylmethyl cellulose (HPMC), or a mixture thereof);sterilization such as autoclave at from 118 to 124° C. for at leastabout 30 minutes; and the like.

A silicone hydrogel contact lens of the invention has a water content offrom about 20% to about 75% (preferably from about 25% to about 70%,more preferably from about 30% to about 65%) by weight when fullyhydrated, an oxygen permeability (Dk) of at least about 40 barrers(preferably at least about 50 barrers, more preferably at least about 60barrers, and even more preferably at least about 70 barrers), and ahydrophilic surface characterized by an average water contact angle ofabout 90 degrees or less (preferably about 80 degrees or less, morepreferably 70 degrees or less, even more preferably about 60 degrees orless) without post molding surface treatment.

A contact lens of the invention can further have at least one propertyselected from the group consisting of an elastic modulus of from about0.1 MPa to about 2.0 MPa, preferably from about 0.2 MPa to about 1.5MPa, more preferably from about 0.3 MPa to about 1.2 MPa, even morepreferably from about 0.4 MPa to about 1.0 MPa; an Ionoflux DiffusionCoefficient, D, of, preferably at least about 1.0×10⁻⁵ mm²/min, morepreferably at least about 2.0×10⁻⁵ mm²/min, even more preferably atleast about 6.0×10⁻⁵ mm²/min; and combinations thereof.

It should be understood that although in this aspect of the inventionvarious embodiments including preferred embodiments of the invention maybe separately described above, they can be combined and/or used togetherin any desirable fashion to arrive at different embodiments of asilicone hydrogel contact lenses of the invention. All of the variousembodiments described above for the previous aspect of the invention canbe used alone or in combination in any desirable fashion in this aspectof the invention.

In a further aspect, the invention provides a method for making siliconehydrogel contact lenses. The method comprises the steps of: introducinga lens formulation into a mold for making contact lenses, wherein thelens-forming formulation comprises (a) an opthalmically compatiblesolvent selected from the group consisting of water, 1,2-propyleneglycol, a polyethyleneglycol having a molecular weight of about 400Daltons or less, and mixtures thereof, and (b) a water-processablepolysiloxane-containing polymerizable material selected from the groupconsisting of a prepolymer of the invention as described above, asiloxane-containing vinylic monomer of formula (2) described above, asiloxane-containing vinylic monomer of formula (3) described above, acrosslinker of formula (7) described above, a crosslinker of formula (8)described above, and combinations thereof, in which B₁ to B₁₄independent of each other area linear or 3-arm hydrophilic polymer chainhaving a molecular weight of about 10,000 Daltons or less (preferablyabout 7500 daltons or less, more preferably about 5000 daltons or less,even more preferably about 2500 Daltons or less, most preferably about1000 Daltons or less) and comprising at least about 60%, preferably atleast about 70%, more preferably at least about 80%, even morepreferably at least about 90%) by weight of one or more hydrophilicmonomeric units selected from the group consisting of ethyleneoxideunits, (meth)acrylamide units, C₁-C₃ alkyl (meth)acrylamide units,di-(C₁-C₃ alkyl) (meth)acrylamide units, N-vinylpyrrole units,N-vinyl-2-pyrrolidone units, 2-vinyloxazoline units, 4-vinylpyridineunits, mono-C₁-C₄ alkoxy, mono-(meth)acryloyl terminatedpolyethyleneglycol units having a molecular weight of 600 Daltons orless, di(C₁-C₃ alkyl amino)(C₂-C₄ alkyl) (meth)acrylate units, N—C₁-C₄alkyl-3-methylene-2-pyrrolidone units, N—C₁-C₄alkyl-5-methylene-2-pyrrolidone units, N-vinyl C₁-C₆ alkylamide units,N-vinyl-N—C₁-C₆ alkyl amide units, and combinations thereof, providedthat the lens-forming formulation is free of any non-ophthalmicallycompatible solvent; polymerizing the lens formulation in the mold toform a silicone hydrogel contact lens, wherein the formed siliconehydrogel contact lens has a water content of from about 20% to about 75%(preferably from about 25% to about 70%, more preferably from about 30%to about 65%) by weight when fully hydrated, an oxygen permeability (Dk)of at least about 40 barrers (preferably at least about 50 barrers, morepreferably at least about 60 barrers, and even more preferably at leastabout 70 barrers), and optionally (but preferably) a hydrophilic surfacecharacterized by an average water contact angle of about 90 degrees orless (preferably about 80 degrees or less, more preferably 70 degrees orless, even more preferably about 60 degrees or less) without postmolding surface treatment. Preferably, the lens forming formulationfurther comprises one or more components selected from the groupconsisting of a hydrophilic vinylic monomer, a hydrophobic vinylicmonomer, a crosslinking agent having a molecular weight of less than 700Daltons, a polymerizable UV-absorbing agent, a visibility tinting agent(e.g., dyes, pigments, or mixtures thereof), antimicrobial agents (e.g.,preferably silver nanoparticles), a bioactive agent, leachablelubricants, leachable tear-stabilizing agents, and mixtures thereof.

Various embodiments of water-processable prepolymers, lens formingformulations, hydrophilic vinylic monomers, hydrophobic vinylicmonomers, solvents, crosslinking agents, polymerizable UV-absorbingagents, photoinitiators, visibility tinting agents, antimicrobialagents, bioactive agents, leachable lubricants, leachabletear-stabilizing agents, molds, polymerizing techniques, and postmolding processes are described above and can be used in this aspect ofthe invention.

In a preferred embodiment, the resultant silicone hydrogel contact lensis extracted with water or an aqueous solution.

In another preferred embodiment, the mold is a reusable mold, thelens-forming composition is cured (i.e., polymerized) actinically undera spatial limitation of actinic radiation to form a silicone hydrogelcontact lens, and the reusable mold is cleaned with an ophthalmicallycompatible fluid selected from the group consisting of water, an aqueoussolution, 1,2-propylene glycol, a polyethyleneglycol having a molecularweight of about 400 Daltons or less, and combination thereof.

Examples of preferred reusable molds are those disclosed in U.S. patentapplication Ser. No. 08/274,942 filed Jul. 14, 1994, Ser. No. 10/732,566filed Dec. 10, 2003, Ser. No. 10/721,913 filed Nov. 25, 2003, and U.S.Pat. No. 6,627,124, which are incorporated by reference in theirentireties. Reusable molds can be made of quartz, glass, sapphire, CaF₂,a cyclic olefin copolymer (such as for example, Topas® COC grade8007-S10 (clear amorphous copolymer of ethylene and norbornene) fromTicona GmbH of Frankfurt, Germany and Summit, N.J., Zeonex® and Zeonor®from Zeon Chemicals LP, Louisville, Ky.), polymethylmethacrylate (PMMA),polyoxymethylene from DuPont (Delrin), Ultem® (polyetherimide) from G.E.Plastics, PrimoSpire®, and combinations thereof.

The molded contact lenses can further subject to further processes, suchas, for example, packaging in lens packages with a packaging solutionwhich can contain about 0.005% to about 5% by weight of a wetting agent(e.g., a hydrophilic polymer described above or the like known to aperson skilled in the art) and/or a viscosity-enhancing agent (e.g.,methyl cellulose (MC), ethyl cellulose, hydroxymethylcellulose,hydroxyethyl cellulose (HEC), hydroxypropylcellulose (HPC),hydroxypropylmethyl cellulose (HPMC), or a mixture thereof);sterilization such as autoclave at from 118 to 124° C. for at leastabout 30 minutes; and the like.

The resultant silicone hydrogel contact lens can further have at leastone property selected from the group consisting of an elastic modulus offrom about 0.1 MPa to about 2.0 MPa, preferably from about 0.2 MPa toabout 1.5 MPa, more preferably from about 0.3 MPa to about 1.2 MPa, evenmore preferably from about 0.4 MPa to about 1.0 MPa; an IonofluxDiffusion Coefficient, D, of, preferably at least about 1.0×10⁻⁵mm²/min, more preferably at least about 2.0×10⁻⁵ mm²/min, even morepreferably at least about 6.0×10⁻⁵ mm²/min.

It should be understood that although in this aspect of the inventionvarious embodiments including preferred embodiments of the invention maybe separately described above, they can be combined and/or used togetherin any desirable fashion to arrive at different embodiments of asilicone hydrogel contact lenses of the invention. All of the variousembodiments described above for the previous aspects of the inventioncan be used alone or in combination in any desirable fashion in thisaspect of the invention.

The previous disclosure will enable one having ordinary skill in the artto practice the invention. In order to better enable the reader tounderstand specific embodiments and the advantages thereof, reference tothe following non-limiting examples is suggested. However, the followingexamples should not be read to limit the scope of the invention.

Although various embodiments of the invention have been described usingspecific terms, devices, and methods, such description is forillustrative purposes only. The words used are words of descriptionrather than of limitation. It is to be understood that changes andvariations may be made by those skilled in the art without departingfrom the spirit or scope of the present invention, which is set forth inthe following claims. In addition, it should be understood that aspectsof the various embodiments may be interchanged either in whole or inpart or can be combined in any manner and/or used together. Therefore,the spirit and scope of the appended claims should not be limited to thedescription of the preferred versions contained therein.

Example 1 Oxygen Permeability Measurements

The apparent oxygen permeability of a lens and oxygen transmissibilityof a lens material is determined according to a technique similar to theone described in U.S. Pat. No. 5,760,100 and in an article by Wintertonet al., (The Cornea: Transactions of the World Congress on the Cornea111, H. D. Cavanagh Ed., Raven Press: New York 1988, pp 273-280), bothof which are herein incorporated by reference in their entireties.Oxygen fluxes (J) are measured at 34° C. in a wet cell (i.e., gasstreams are maintained at about 100% relative humidity) using a Dk1000instrument (available from Applied Design and Development Co., Norcross,Ga.), or similar analytical instrument. An air stream, having a knownpercentage of oxygen (e.g., 21%), is passed across one side of the lensat a rate of about 10 to 20 cm³/min., while a nitrogen stream is passedon the opposite side of the lens at a rate of about 10 to 20 cm³/min. Asample is equilibrated in a test media (i.e., saline or distilled water)at the prescribed test temperature for at least 30 minutes prior tomeasurement but not more than 45 minutes. Any test media used as theoverlayer is equilibrated at the prescribed test temperature for atleast 30 minutes prior to measurement but not more than 45 minutes. Thestir motor's speed is set to 1200±50 rpm, corresponding to an indicatedsetting of 400±15 on the stepper motor controller. The barometricpressure surrounding the system, P_(measured), is measured. Thethickness (t) of the lens in the area being exposed for testing isdetermined by measuring about 10 locations with a Mitotoya micrometerVL-50, or similar instrument, and averaging the measurements. The oxygenconcentration in the nitrogen stream (i.e., oxygen which diffusesthrough the lens) is measured using the DK1000 instrument. The apparentoxygen permeability of the lens material, Dk_(app), is determined fromthe following formula:Dk _(app) =Jt/(P _(oxygen))where J=oxygen flux [microliters O₂/cm²-minute]

P_(oxygen)=(P_(measured)−P_(water) vapor)=(% O₂ in air stream) [mmHg]=partial pressure of oxygen in the air stream

P_(measured)=barometric pressure (mm Hg)

P_(water) vapor=0 mm Hg at 34° C. (in a dry cell) (mm Hg)

P_(water) vapor=40 mm Hg at 34° C. (in a wet cell) (mm Hg)

t=average thickness of the lens over the exposed test area (mm)

Dk_(app) is expressed in units of barrers.

The apparent oxygen transmissibility (Dk/t) of the material may becalculated by dividing the apparent oxygen permeability (Dk_(app)) bythe average thickness (t) of the lens.

The above described measurements are not corrected for the so-calledboundary layer effect which is attributable to the use of a water orsaline bath on top of the contact lens during the oxygen fluxmeasurement. The boundary layer effect causes the reported value for theapparent Dk (Dk_(app)) of a silicone hydrogel material to be lower thanthe actual intrinsic Dk value (Dk_(i)). Further, the relative impact ofthe boundary layer effect is greater for thinner lenses than withthicker lenses. The net effect is that the reported Dk appear to changeas a function of lens thickness when it should remain constant.

The intrinsic Dk value of a lens can be estimated based on a Dk valuecorrected for the surface resistance to oxygen flux caused by theboundary layer effect as follows.

Measure the apparent oxygen permeability values (single point) of thereference Iotrafilcon A (Focus® N&D® from CIBA VISION CORPORATION) orIotrafilcon B (AirOptix™ from CIBA VISION CORPORATION) lenses using thesame equipment. The reference lenses are of similar optical power as thetest lenses and are measured concurrently with the test lenses.

Measure the oxygen flux through a thickness series of Iotrafilcon A orIotrafilcon B (reference) lenses using the same equipment according tothe procedure for apparent Dk measurements described above, to obtainthe intrinsic Dk value (Dk_(i)) of the reference lens. A thicknessseries should cover a thickness range of approximately 100 μm or more.Preferably, the range of reference lens thicknesses will bracket thetest lens thicknesses. The Dk_(app) of these reference lenses must bemeasured on the same equipment as the test lenses and should ideally bemeasured contemporaneously with the test lenses. The equipment setup andmeasurement parameters should be held constant throughout theexperiment. The individual samples may be measured multiple times ifdesired.

Determine the residual oxygen resistance value, R_(r), from thereference lens results using equation (I) in the calculations.

$\begin{matrix}{R_{r} = \frac{\sum\;\left( {\frac{t_{j}}{{Dk}_{app}} - \frac{t_{j}}{{Dk}_{i}}} \right)}{n}} & (I)\end{matrix}$In which t is the thickness of a reference lens under measurement, and nis the number of the reference lenses measured. Plot the residual oxygenresistance value, R_(r) vs. t data and fit a curve of the form Y=a+bXwhere, for the jth lens, Y_(j)=(ΔP/J)_(j) and X=t_(j). The residualoxygen resistance, R_(r) is equal to a.

Use the residual oxygen resistance value determined above to calculatethe correct oxygen permeability Dk_(c) (estimated intrinsic Dk) for thetest lenses based on Equation (II).Dk _(c) =t/[(t/Dk _(a))−R _(r)]  (II)

The estimated intrinsic Dk of the test lens can be used to calculatewhat the apparent Dk (Dk_(a) _(_) _(std)) would have been for a standardthickness lens in the same test environment based on Equation (Ill).Dk _(a) _(_) _(std) =t _(std)/[(t _(std) /Dk _(c))+R _(r) _(_)_(std)]  (III)Ion Permeability Measurements.

The ion permeability of a lens is measured according to proceduresdescribed in U.S. Pat. No. 5,760,100 (herein incorporated by referencein its entirety. The values of ion permeability reported in thefollowing examples are relative ionoflux diffusion coefficients(D/D_(ref)) in reference to a lens material, Alsacon, as referencematerial. Alsacon has an ionoflux diffusion coefficient of 0.314×10⁻³mm²/minute.

Water Contact Angle (WCA) Measurements.

Water contact angle (WCA) measurements are performed by the sessile dropmethod with a DSA 10 drop shape analysis system from Krüss GmbH, Germanywith pure water (Fluka, surface tension 72.5 mN/m at 20° C.). Formeasurement purposes a contact lens is taken off the storage solutionwith tweezers and excess storage solution is removed by gentle shaking.The contact lens are placed on the male part of a lens mold and gentlyblotted with a dry and clean cloth. A water droplet (approximately 1 μl)is then dosed on the lens apex, and the change of the contact angle overtime of this water droplet (WCA(t), circle fitting mode) is monitored.The WCA is calculated by the extrapolation of the graph WCA(t) to t=0.

UV-Absorbance. Contact lenses are manually placed into a speciallyfabricated sample holder or the like which can maintain the shape of thelens as it would be when placing onto eye. This holder is then submergedinto a 1 cm path-length quartz cell containing phosphate buffered saline(PBS, pH˜7.0-7.4) as the reference. A UV/visible spectrophotometer, suchas, Varian Cary 3E UV-Visible Spectrophotometer with a LabSphereDRA-CA-302 beam splitter or the like, can be used in this measurement.Percent transmission spectra are collected at a wavelength range of250-800 nm with % T values collected at 0.5 nm intervals. This data istransposed onto an Excel spreadsheet and used to determine if the lensesconform to Class 1 UV absorbance. UV absorbance is calculated using thefollowing equations:

${{UVA}\mspace{14mu}\% T} = {\frac{{Average}\mspace{14mu}\%\mspace{14mu} T\mspace{14mu}{between}\mspace{14mu} 380\text{-}316\mspace{14mu}{nm}}{{Luminescence}\mspace{14mu}\% T} \times 100}$${{UVB}\mspace{14mu}\% T} = {\frac{{Average}\mspace{14mu}\%\mspace{14mu} T\mspace{14mu}{between}\mspace{14mu} 280\text{-}315\mspace{14mu}{nm}}{{Luminescence}\mspace{14mu}\% T} \times 100}$In which Luminescence % T is the average % transmission between 380 and780.

Example 2

A one-liter reaction vessel is evacuated overnight to remove moisture,and the vacuum broken with dry nitrogen. 73.59 g (75 meq) of driedX-22-160AS (α,ω-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane,M.W.˜1000, from Shin-Etsu) is charged to the reactor and then about16.67 g (75 meq) of freshly distilled isophorone diisocyanate (IPDI) isadded into the reactor. The reactor is purged with nitrogen and heatedto 45° C. with stirring and about 0.30 g of dibutyltin dilaurate (DBTDL)is added. The reactor is sealed, and a positive flow of nitrogen ismaintained. An exotherm occurs, after which the reaction mixture isallowed to cool and stir at 55° C. for 2 hours. About 56.25 g (75 meq)of dried mono-methoxy-terminated polyethylene glycol, M.W.˜750) is addedto the reactor at 55° C., followed by 100 μL of DBTDL. The reaction iscontinued for 8 hours before heating is discontinued and the reactor isallowed to cool overnight. The nitrogen bubble is discontinued and thereactor is filled with dry air with moderate stirring. The formedproduct contains hydroxy-terminated block copolymer containing onepolysiloxane segment and one PEG 750 segment as main components. About11.63 g (75 meq) of IEM is added to the reactor along with 100 μL ofDBTDL. The reaction is continued under dry air with moderate stirringfor 24 hours, leading to a product majorly containing methacrylate endedPDMS and PEG block copolymer (MA-PDMS1000-PEG750), and then the productis decanted and stored under refrigeration.

Example 3

A one-liter reaction vessel is evacuated overnight to remove moisture,and the vacuum broken with dry nitrogen. 73.59 g (75 meq) of driedX-22-160AS (α,ω-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane,M.W.˜1000, from Shin-Etsu) is charged to the reactor and then about39.23 g (176.5 meq) of freshly distilled isophorone diisocyanate (IPDI)is added into the reactor. The reactor is purged with nitrogen andheated to 45° C. with stirring and then about 0.30 g of dibutyltindilaurate (DBTDL) is added. The reactor is sealed, and a positive flowof nitrogen is maintained. An exotherm occurs, after which the reactionmixture is allowed to cool and stir at 55° C. for 2 hours. About 72.12 g(66.20 meq) of dried Ymer™ N120 (mono-3,3-bis(hydroxymethyl)butyl- andmono-methoxy-terminated polyethylene glycol, M.W.˜1000, from PerstorpPolyols, Inc.) is added to the reactor at 55° C., followed by 100 μL ofDBTDL. The reaction is continued for 8 hours before heating isdiscontinued and the reactor is allowed to cool overnight. The nitrogenbubble is discontinued and the reactor is filled with dry air withmoderate stirring. An α,ω-bis(isocyanate)-terminated chain extendedpolysiloxane having multiple segments of polysiloxane and pendent PEG1000 chains is formed. About 9.83 g (75 meq) of 2-hydroxyethylmethacrylate (HEMA) is added to the reactor, along with 100 μL of DBTDL.The reaction is continued under dry air with moderate stirring for 24hours, leading to a hydrophilized chain-extended polysiloxanecrosslinker (YMER 50X) having the formula of

in which Y₈ is —C(O)—O—C₂H₄—O—C(O)—NH—Z₃—NH—C(O)—O—, Y₁₇ is—O—C(O)—NH—Z₃—NH—C(O)—O—C₂H₄—O—C(O)— in which Z₃ is a divalent radicalof

Y₉, Y₁₀, Y₁₁ and Y₁₆ independent of each other are—O—C(O)—NH—Z₃—NH—C(O)—O— in which Z₃ is as defined above, D₃ and D₄ area divalent radical of

e3 and e7 independent of each other are integer of 0, 1 or 2, e4 is aninteger of 1 or 2, d2 is an integer of 0 to about 10, m is an integer ofabout 15 to 29, m1 is an integer of about 7 to about 14. The numberaverage molecular weight of YMER 50X is determined to be about 12,000Daltons based on conventional GPC using DMF as the eluent andpolystyrene as the standard. The product is decanted and stored underrefrigeration.

Examples 4 to 10

Various lens forming formulations are prepared in a 20 mL amber vial tohave compositions shown in Table 1. The homogenization of the mixture isachieved via rolling on the roller overnight.

TABLE 1 Silicone-containing component DC- Example I II III IV DMA EGDMA1173 Solvent 4 3.1 4.7 0.2 0.1 1.9^(a) 5 4.7 3.1 0.2 0.1 1.9^(a) 6 1.552.35 0.1 0.05 0.95^(b) 7 2.35 1.55 0.1 0.05 0.95^(b) 8 0.9 3 0.1 0.050.95^(b) 9 0.9 3 0.1 0.05 0.95^(b) 10 1.65 2.25 0.1 0.05 0.95^(b) DMA:N,N-dimethyl acrylamide; EGDMA: Ethyleneglycol dimethacrylate; DC-1173:Darocur 1173. ^(a)1,2-propylene glycol; ^(b)1-propanol Siliconecontaining component: I is SiGMA (methyl bis(trimethylsiloxy)silyl]propyl glycerol methacrylate); II is Hydroxy-4 (as shown above); III isa hydrophilized chain-extended polysiloxane crosslinker prepared inExample 3; and IV is MA-PDMS1000-PEG750.

A lens forming formulation is placed in polypropylene plastic molds andcured under UV light (3.8 mW/cm²) for about 15 minutes to form contactlenses. The lens de-molding is achieved by soaking the molds with lensesin 2-propanol/water (30/70 v/v) for about 10 minutes. The lenses areextracted with DI water for about 5 minutes. The lenses are stored inPBS in the glass vial and autoclaved at about 120° C. for about 30minutes. Oxygen permeability (Dk_(c)), water content (WC %), relativeionoflux diffusion coefficients (D/D_(ref)) in reference to Alsacon asreference lens material (IP_(ref)), and average water contact angle aremeasured according to the procedures described in Example 1. The resultsare shown in Table 2.

TABLE 2 Example Lens Property 3 4 5 6 7 8 9 Dk_(c) (barrers) 49 32 50 2935 61 31 WC % (w/w) 33 53 52 61 49 48 54 IP 0.3 15.3 5.2 NA NA 15.5 NAWCA (degrees) NA NA 106 109 81 55 NA

Experiments carried out in Examples 4-10 may provide guidance to selecta polymerizable composition to make a water-processable prepolymer,which is suitable for making silicone hydrogel contact lenses havingdesired oxygen permeability, water content, surfacehydrophilicity/wettability without any post molding surface treatment,and ion permeability.

Example 11

This example illustrates the water-solubility of intermediary copolymerswhich can be ethylenically functionalized to form prepolymers.

An intermediary copolymer is prepared by thermally polymerizing apolymerizable composition having the polymerizable contents shown inTable 3 according to a procedure used to prepare sample 11 as follows.

TABLE 3 Polymerizable component (% w/w)* Ymer MA-PDMS1000- MA- SampleSIGMA 50X PEG750 PDMS Hydroxy 4 DMA 1 35 20 45 2 40 20 40 3 20 40 40 417 35 47 5 22 35 42 6 22 42 36 7 35 45 25 8 20 20 60 9 20 20 10 50 10 2040 40 11 40 20 40 *Each sample also contains about 0.73% (w/w) of APMAwhich can be used for covalent attachment of ethylenically unsaturatedgroup relative to the total amount of all polymerizable components.

A 1-L jacketed reactor equipped with a heating/chilling loop, refluxcondenser with N₂-inlet adapter, N₂ inlet adapter, 250 mL additionalfunnel, a thermocouple adaptor, and overhead stirring is used. Add allthe polymerizable components including 40 g of YMER 50X, 20 g of hydroxy4, 40 g of DMA, and 233 g of methanol and thoroughly mix them. Chill themixture with stirring until the solution temperature gets between 0 to−5° C. The solution is degassed by purging with N₂ for 1 hour. 0.09 g ofazo-bis(isobutyronitrile) (AIBN) and 0.26 g 2-mercaptoethanol, 0.74 g ofN-(3-aminopropyl)methylacrylamide hydrochloride (APMA) are dissolved in50 g of methanol in a 100 mL beaker. This initiator/CTA solution is thentransferred to the additional funnel connected to the reactor. Thissolution is degassed three times by evacuation to 100 mBar, holdingvacuum for 10 minutes, and then re-pressurizing with nitrogen. Aftercompletion of N₂ purge, the reactor is then heated to 60° C. and thesolution is charged to the reactor at this point. After 8 hours, thereaction mixture is then cooled to room temperature and the solvent wasremoved via rotavap at 50 mbar and 30° C. The final wax like product isobtained.

Solubility Test:

The obtained intermediary copolymers are characterized to determinetheir water solubility and clarity (Table 4). The solubility test iscarried out by adding 0.1 g of copolymer in 10 mL of water and stirringit overnight.

TABLE 4 1 2 3 4 5 6 7 8 9 10 11 Silicone 29 32 28 25 24 31 40 28 28 3730 % (w/w) Water yes No Yes Yes Yes Yes No No Yes No Yes solubilityClarity a d b a b b d d c d a Note: a-slightly hazy; b-clear; c-hazy;d-not soluble.

Sample 4 is further studied to determine the feasibility of formulationin water or low and non-toxic organic solvents such as 1,2-propyleneglycol and PEG 200 (Table 5). The formulations are prepared in a 5 mLamber vial to have compositions shown in Table 5. The homogenization ofthe mixture is achieved by first heating the solution to 50° C. for halfhour and then rolling it on the roller overnight. Clear formulations areobtained using either 1,2-propylene glycol or PEG 200 as the solvent,while formulation in water is hazy.

TABLE 5 1.2-propylene Test Polymer Water glycol PEG 200 % Appearance 10.5 0.5 50 Haze 2 0.5 0.5 50 Clear 3 0.4 0.417 49 ClearMold Cleaning:

The above formulations in PEG 200 and 1,2-propylene glycol are used formold cleaning study. One or two drops of formulation are deposited on amale Quartz mold and then cleaned it with DI water either through washbottle or water machine. The mold surface is then inspected withmicroscope. The results are shown in (Table 6). In most cases, the moldscan be efficiently cleaned.

TABLE 6 Water (RT) Water (40° C.) Bottle Machine Bottle Machine Test (60s) (30-40 s) (60 s) (20 s) 2 Small residual Clean Clean Clean 3 CleanClean Clean Clean

Example 12

A one-liter reaction vessel is evacuated overnight to remove moisture,and the vacuum broken with dry nitrogen. 73.59 g (75 meq) of driedX-22-160AS (α,ω-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane,M.W.˜1000, from Shin-Etsu) is charged to the reactor and then about26.68 g (120 meq) of freshly distilled isophorone diisocyanate (IPDI) isadded into the reactor. The reactor is purged with nitrogen and heatedto 45° C. with stirring and then about 0.30 g of dibutyltin dilaurate(DBTDL) is added. The reactor is sealed, and a positive flow of nitrogenis maintained. An exotherm occurs, after which the reaction mixture isallowed to cool and stir at 55° C. for 2 hours. About 23.89 g (21.96meq) of dried Ymer™ N120 (mono-3,3-bis(hydroxymethyl)butyl- andmono-methoxy-terminated polyethylene glycol, M.W.˜1000, from PerstorpPolyols, Inc.) is added to the reactor at 55° C., followed by 100 μL ofDBTDL. The reaction is continued for 2 hours before heating isdiscontinued and the reactor is allowed to cool. About 6.59 g (50.64meq) of 2-hydroxyethyl methacrylate (HEMA) is added to the reactor,along with 100 μL of DBTDL. The reaction is continued under dry air withmoderate stirring for 24 hours, leading to formation of hydrophilizedchain-extended polysiloxane crosslinkers (YSX-75) having the formula of

in which Y₈ and Y₁₇ are a divalent radical of—C(O)—O—C₂H₄—O—C(O)—NH—Z₃—NH—C(O)—O— and—O—C(O)—NH—Z₃—NH—C(O)—O—C₂H₄—O—C(O)— respectively, in which Z₃ is adivalent radical of

D₃, D₄, and D₅ are a divalent radical of

Y₁₀, Y₁₁, Y₁₂, Y₁₃ and Y₂₈ independent of one another are—O—C(O)—NH—Z₃—NH—C(O)—O— in which Z₃ is as defined above, A₈ and A₈′ are—C₂H₄OC₃H₆—, A₉ and A₉′ are —C₃H₆OC₂H₄—, m is an integer of about 15 to29, m1 and m2 independent of each other are an integer of about 7 toabout 14, f1 is an integer of 0 to 9, d2 and d3 independent of eachother are an integer of 0 to 10. The number average molecular weight ofYSX-75 is determined to be about 17,000 Daltons based on conventionalGPC using DMF as the eluent and polystyrene as the standard. The productis decanted and stored under refrigeration.

Example 13 Copolymer/Macromer Synthesis

A 500-mL jacketed reactor is equipped with a heating/chilling loop,septum inlet adapter, reflux condenser with N₂-inlet adapter, vacuumline and overhead stirring. 25.6 g of hydrophilized chain-extended PDMScrosslinker (YSX-75, prepared in Example 12), is prepared as a 50%solution in t-amyl alcohol and then charged to the reaction vessel. Thesolution is degassed under vacuum less than 1 mBar for 5 minutes, andthen re-pressurizing with dry nitrogen. This degas procedure is repeatedfor a total of 6 times.

A monomer solution is prepared by dissolving 5.76 g of methylbis(trimethylsiloxy)silyl]propyl glycerol methacrylate (SiGMA), 1.50 gof methacrylic acid, 13.67 g of N,N-dimethylacrylamide and 1.23 g ofaminopropyl methacrylamide hydrochloride salt in a mixture of 1.23 g ofDI water and 175 g of t-amyl alcohol. This monomer solution istransferred to an additional funnel sitting on top of reaction vesselfollowed with a degas process under vacuum at 100 mBar for 10 minutes,and then re-pressurizing with dry nitrogen. This degas procedure isrepeated for a total of 3 times.

An initiator and chain-transfer agent (CTA) pot solution is prepared bymixing 0.15 g of azo-bis(isobutyronitrile) pre-dissolved in 37.50 g oft-Amyl alcohol and 0.755 g of cysteamine hydrochloride pre-dissolved in0.60 g of DI water and 1.80 g of methanol is degassed under vacuum at100 mBar for 10 minutes, and then re-pressurizing with dry nitrogen.This degas procedure is repeated for a total of 3 times.

The CTA feed solution is prepared by dissolving 1.136 g of cysteaminehydrochloride in 0.90 g of DI water, 2.25 g of methanol and 56.25 g oft-amyl alcohol.

After both YSX-75 solution and monomer solution are degassed, themonomer solution is charged to the reaction vessel. Temperature of themixed solution is then quickly elevated from room temperature to 64° C.The initiator/CTA solution is injected to the system when thetemperature close to 64° C. and CTA feed solution is fed over 2 hoursthrough a combination of degas unit and HPLC pump. The reaction mixtureis maintained at 64° C. under nitrogen for 5 hours after the initiatorsolution is injected. After the copolymerization is done and thetemperature is cooled to room temperature, the reaction solvent isexchanged to isopropyl alcohol and then to water as a 2 liter solution.The copolymer solution is purified by ultrafiltration and then chargedto a 2-L reactor equipped with overhead stirring, refrigeration loop,thermometer, and the pH meter and dispensing tip of a Metrohm Model 718STAT Titrino. The reaction mixture is then cooled to 1° C. 4.8 g ofNaHCO₃ are charged to the solution and stirred to dissolve. The Titrinois set to maintain pH at 9.5 by intermittent addition of 20% sodiumhydroxide solution. Acryloyl chloride, 9.6 mL, is then added over 2 hourusing a syringe pump. After the solution is stirred for another hour,the Titrino is set to neutralize the reaction mixture by addition of a 2N hydrochloric acid. The macromer solution is then filtered and thenpurified with ultrafiltration until the conductivity of permeability isless than 5 μS/cm. The purified macromer solution is then solventexchanged to 1-propanol as a stock solution.

Formulation Composition and Photorheology:

Photorheology Formulation UV Curing Irgacur Solvent Intensity Time G′Viscosity Macromer 2959 DPGME mW/cm² Seconds kPa mPas 60% 0.3% 39.7% 613 150 6875 55% 0.3% 44.7% 6 36 130 2500 55% 0.5% 44.5% 6 19 115 2355DPGME: dipropylene glycol methyl etherLens Fabrication:

The lenses are fabricated in polypropylene lens mold with equivalent UVenergy as provided by photorheology. The lenses are demold in DI waterand then packed in saline solution followed with autoclave at 121° C.for 30 minutes.

Lens Characterization Properties:

Formulation Irgacur Solvent Lens Characterization Macromer 2959 DPGME E′EtB % Dk IP 60% 0.3% 39.7% 0.81 190% 60 19 55% 0.3% 44.7% 0.82 210% 6118 55% 0.5% 44.5% 0.86 220% 62 17

Example 14 Copolymer/Macromer Synthesis

The copolymer and macromer are prepared by the same manner as themacromer of Example 13 except that aminopropyl methacrylamidehydrochloride salt is not used as one of the monomers.

Formulation Composition and Photorheology:

Photorheology Formulation UV Curing Irgacur Solvent Intensity Time G′Viscosity Macromer 2959 DPGME mW/cm² Seconds kPa mPas 60% 0.3% 39.7% 638 89 14800Lens Fabrication:

The lenses are fabricated according to the procedures described inExample 13.

Lens Characterization Properties:

Formulation Irgacur Solvent Lens Characterization Macromer 2959 DPGME E′EtB % Dk IP 60% 0.3% 39.7% 0.42 260% 52 36

Example 15 A: Chain-Extended PDMS Cross-Linker with Pendant p(DMA)Chains

Mono-dihydroxyl terminated poly(N,N-dimethylacrylamide) (poly(DMA)) isprepared by radical polymerization using 3-mercapto-1,2-propanediol aschain transfer reagent, as shown in the following scheme

In a typical experiment, DMA (15.861 g, 160 mmol), AIBN (0.263 g, 1.44wt % of monomers), 3-mercapto-1,2-propanediol (2.388 g, 22.08 mmol), andtoluene (42.80 mL) are introduced into a 250 mL Pyrex round flask. Thesolution is purged with N₂ gas for 30 min before polymerization iscarried out at 65° C. for 12 h. The product is dialyzed in 2 L tolueneusing MWCO 500 Cellulose Ester (Spectra/Por® Biotec) tube for 12 hours.The final product is precipitated into ethyl ether, decanted, and driedunder vacuum. The number average molecular weight of the final polymerwas 383 g/mol based on GPC using THF as the eluent and polystyrene asthe standards.

Intermediary copolymers having PDMS segments and pendant poly(DMA)chains and terminated with isocyanate group is synthesized viacondensation reaction between a mono-bishydroxyl terminated poly(DMA)(4.50 g) prepared above and di-hydroxyl terminated PDMS (7.00 g) inpresence of 1,6-hexamethylene diisocyanate (2.51 g) and catalyticalamount of Dibutyltindilaurate (DBTDL) (0.075%) in 14 g of toluene at 40°C. for 2 hours. Reactions are allowed to proceed until percentage of NCOby titration is close to theoretically predicted values.

Isocyanate terminated intermediary copolymers are then converted to acrosslinker in a second step through reaction with N-hydroxylethylacrylamide (HEAA) (0.69 g) at room temperature for 5-6 hrs. Theresulting crosslinkers are dialyzed in methanol followed by ethylacetate using MWCO 3,500 regenerator cellulose tube. Final crosslinkeris kept in solution with OH-TEMPO inhibitor (100 ppm against thepolymer). The number average molecular weight of the final polymer is7,160 g/mol based on GPC using THF as the eluent andpolydimethylsiloxane as the standards.

B: Chain-Extended PDMS Cross-Linker with Pendant p(DMA) Chains

44.46 g (448.0 mmol) of DMA, 0.184 g (1.12 mmol) of AIBN, 6.726 g,(61.82 mmol) of 3-mercapto-1,2-propanediol, 102.6 g of Toluene and 10.29g of ethyl acetate are introduced into a 250 ml round flask. Afterdegassing by nitrogen bubbling for 1.0 h, polymerization is carried outat 55° C. for 12 h. The product is dialyzed in toluene using MWCO 500Cellulose Ester (Spectra/Por® Biotec) tube for 12 h. Final product isprecipitated into hexane, decanted, and dried under vacuum. The numberaverage molecular weight of the final polymer is 541 g/mol based on GPCusing THF as the eluent and polystyrene as standards.

To dried 250 ml flask, 28.0 g (29.3 mmol) of purified Shin-Etsu 160AS,24.0 g (29.0 mmol) of mono-dihydroxyl terminated poly(DMA) aboveprepared and 64.0 g toluene are added. The flask is placed in 40° C. oilbath with stirring until dissolution. After cooling down to roomtemperature, 11.81 g (69.88 mmol) of hexamethylene diisocyanate with 3drops of Dibutyltindilaurate (DBTDL) are added. Reaction is preceded in40° C. oil bath for about 2 hrs and NCO conversion is monitored bytitration until close to theoretical value. Cooled down again to roomtemperature and then 3.256 g (27.95 mmol) of HEAA is added with 3 dropscatalyst to react overnight. Product is dialyzed in methanol and ethylacetate, respectively using MWCO 3,500 regenerator cellulose tube. Finalmacromer is kept in solution with H-tempo inhibitor for solid contentdetermination, formulation and lens fabrication. The number averagemolecular weight of the final polymer is 7,464 g/mol based on GPC usingTHF as the eluent and polydimethylsiloxane as the standards.

C. Formulation and Lens Casting

Formulations are prepared by dissolving a chain-extended PDMScrosslinker with pendant p(DMA) chains in dipropylene glycol methylether (DPGME) to have a concentration of about 60% by weight. Eachformulation also contains 0.3% by weight of Irgacure 2959. Typicalconditions for formulation photo-rheology and lens production are about4-10 seconds at 4-6 mW/cm² with 297 nm filter cut off depended on moldtype used. The molded lenses are characterized and properties arereported in Table 7.

TABLE 7 Properties Crosslinker A Crosslinker B G′ (kPa) 131 164 Curingtime (s) 6 4 Viscosity (mPa · S) 2,820 4,130 Modulus (MPa) 1.05 1.07Maximum Elongation (%) 217 209 Dkc (Barrer) 125 83 IP (relative toAlsacon) 0.9 7.6 Water % 34 39 Lubricity — 2

D: Mold Cleaning

All above formulations are used for mold cleaning study. After lensesare made using the Quartz mold, the mold is rinsed with tap water. Themold is then examined with OptiSpec microscope. In most cases, the moldsare efficiently cleaned.

What is claimed is:
 1. A silicone hydrogel contact lens obtained bycuring a lens forming formulation including a water-processableprepolymer which comprises: (1) polysiloxane-containing crosslinkingunits, wherein the polysiloxane-containing crosslinking units arederived from at least one hydrophilized polysiloxane crosslinker and/orchain-extended hydrophilized polysiloxane crosslinker of formula (7) or(8); (2) hydrophilic monomeric units derived from one or morehydrophilic vinylic monomers; (3) from about 0.05% to about 5% by weightof polymerizable units each having a pendant or terminal,ethylenically-unsaturated group and free of any polysiloxane segment;and (4) optionally hydrophobic units derived from at least onehydrophobic vinylic monomer free of silicone,

in which d2, d3, d4, ω1, ω2, and ω3 independent of one another are aninteger from 0 to 20; e3, e4, e5, e6, e7, υ1, υ2, υ3, υ4, and υ5independent of one other are 0, 1, 2 or 3 and (e3+e4+e5+e6+e7)≧1 and(υ1+υ2+υ3+υ4+υ5)≧1; X₁ is hydrogen or methyl; D₃, D₄, D₅, D₆, D₇, D₈,D₉, and D₁₀ independently of one other are a divalent group of formula(9)

in which Y₂₈ is as defined below, A₈, A₈′, A₉, and A₉′ independent ofone other are a direct bond, a linear or branched C₁-C₁₀ alkylenedivalent radical, —(CH₂CH₂O)_(r1)—CH₂CH₂— in which r1 is an integer of 1to 20, or a C₁-C₇ alkyleneoxy-C₁-C₇ alkylene divalent radical, and R₁,R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₁′, R₂′, R₃′, R₄′, R₅′, R₆′, R₇′, and R₈′independently of one another, are C₁-C₄-alkyl, -alk-(OCH₂CH₂)_(r2)—OR₉in which alk is C₁-C₆-alkylene divalent radical, R₉ is C₁-C₄ alkyl andr2 is an integer from 1 to 20, f1 is an integer of 0 to 8, m1, m2, p1and p2 independently of each other are an integer of from 0 to 150,(m1+p1) and (m2+p2) independent of each other are from 2 to 150; L₄, L₅,L₆, L₇, L₈, L₉, L₁₀, L₁₁, L₁₂, L₁₃, L₁₄, L₁₅, L₁₆, L₁₇, Y₈, Y₉, Y₁₀,Y₁₁, Y₁₂, Y₁₃, Y₁₄, Y₁₅, Y₁₆, Y₁₇, Y₁₈, Y₁₉, Y₂₀, Y₂₁, Y₂₂, Y₂₃, Y₂₄,Y₂₅, Y₂₆, Y₂₇, and Y₂₈ independent of one another are a direct bond or adivalent radical of —Z₁—X₂—Z₂—X₃—Z₃—X₄—Z₄— In which X₂, X₃ and X₄independent of one other are a linkage selected from the groupconsisting of a direct bond, —O—, —NR′— in which R′ is H or C₁-C₄ alkyl,—C(O)—NH—, —NH—C(O)—, —NH—C(O)—NH—, —O—C(O)—NH—, —S—, —NH—C(O)—O—,—C(O)—O—, —O—C(O)—, —NH—C(O)—NH—Z₀—NH—C(O)—NH—,—O—C(O)—NH—Z₀—NH—C(O)—O—, —O—C(O)—NH—Z₀—NH—C(O)—NH—, and—NH—C(O)—NH—Z₀—NH—C(O)—O—, Z₀ is a linear or branched C₂-C₁₂ alkylenedivalent radical or a C₅-C₄₅ cycloaliphatic or aliphatic-cycloaliphaticdivalent radical optionally containing therein one or more linkages of—O—, —NR′—, —S— and —C(O)—, Z₁, Z₂, Z₃ and Z₄ independent of one otherare is a direct bond, a linear or branched C₁-C₁₂ alkylene divalentradical optionally containing therein one or more linkages of —O—,—NR′—, —S— and —C(O)—, a divalent radical of —CH₂—CH(OH)—CH₂— or—(CH₂CH₂O)_(r1)—CH₂CH₂— with r1 as defined above, or a C₅-C₄₅cycloaliphatic or aliphatic-cycloaliphatic divalent radical optionallycontaining therein one or more linkages of —O—, —NR′—, —S— and —C(O)—;B₅, B₆, B₇, B₈, B₉, B₁₀, B₁₁, B₁₂, B₁₃, and B₁₄ independent of oneanother are hydroxyl or a linear or 3-arm hydrophilic polymer chainhaving a molecular weight of about 10000 Daltons or less and comprisingat least about 60% by weight of one or more hydrophilic monomeric unitsselected from the group consisting of ethyleneoxide units,(meth)acrylamide units, C₁-C₃ alkyl (meth)acrylamide units, di-(C₁-C₃alkyl) (meth)acrylamide units, N-vinylpyrrole units,N-vinyl-2-pyrrolidone units, 2-vinyloxazoline units, 4-vinylpyridineunits, mono-C₁-C₄alkoxy, mono-(meth)acryloyl terminatedpolyethyleneglycol units having a molecular weight of 600 Daltons orless, di(C₁-C₃ alkyl amino)(C₂-C₄ alkyl) (meth)acrylate units, N—C₁-C₄alkyl-3-methylene-2-pyrrolidone units, N—C₁-C₄alkyl-5-methylene-2-pyrrolidone units, N-vinyl C₁-C₆ alkylamide units,N-vinyl-N—C₁-C₆ alkyl amide units, and combinations thereof, providedthat at least one of B₅, B₆, B₇, B₈, and B₉ and at least one of B₁₀,B₁₁, B₁₂, B₁₃, and B₁₄ are the linear or 3-arm hydrophilic polymerchain; and T₁, T₂, T₃, T₄, T₅, T₆, T₇, T₈, T₉, T₁₀, T₁₁, T₁₂, T₁₃, andT₁₄ independent of one another are an aliphatic or cycloaliphatic oraliphatic-cycloaliphatic trivalent radical which has up to 15 carbonatoms and can be interrupted by —O—, —NR′—, —C(O)— and/or —S—, whereinthe prepolymer comprises from about 20% to about 50% by weight ofsilicone relative to the total weight of the prepolymer and has a highwater solubility or dispersibility of at least about 5% by weight inwater, wherein the contact lens has at least one property selected fromthe group consisting of a water content of from about 20% to about 75%by weight when fully hydrated, an oxygen permeability (Dk) of at leastabout 40 barrers, a hydrophilic surface characterized by an averagewater contact angle of about 90 degrees or less without post moldingsurface treatment, an elastic modulus of from about 0.1 MPa to about 2.0MPa; an Ionoflux Diffusion Coefficient, D, of, at least about 1.0×10⁻⁵mm²/min; and combinations thereof.
 2. A method for making siliconehydrogel contact lenses, comprising the steps of: (1) introducing a lensformulation into a mold for making contact lenses, wherein thelens-forming formulation comprises (a) a mixture including a hydrophilicvinylic monomer and a polymerizable component selected from the groupconsisting of a crosslinker of formula (7), a crosslinker of formula(8), and combinations thereof,

in which D₃, D₄, D₅, D₆, D₇, D₈, D₉, and D₁₀ independently of one otherare a divalent group of formula (9),

X₁ is hydrogen or methyl, d2, d3, d4, ω1, ω2, and ω3 independent of oneanother are an integer from 0 to 20, e3, e4, e5, e6, e7, υ1, υ2, υ3, υ4,and υ5 independent of one other are 0, 1, 2 or 3 and (e3+e4+e5+e6+e7)≧1and (υ1+υ2+υ3+υ4+υ5)≧1, A₈, A₈′, A₉, and A₉′ independent of one otherare a direct bond, a linear or branched C₁-C₁₀ alkylene divalentradical, —(CH₂CH₂O)_(r1)—CH₂CH₂— in which r1 is an integer of 1 to 20,or a C₁-C₇ alkyleneoxy-C₁-C₇ alkylene divalent radical, and R₁, R₂, R₃,R₄, R₅, R₆, R₇, R₈, R₁′, R₂′, R₃′, R₄′, R₅′, R₆′, R₇′, and R₈′independently of one another, are C₁-C₄-alkyl, -alk-(OCH₂CH₂)_(r2)—OR₉in which alk is C₁-C₆-alkylene divalent radical, R₉ is C₁-C₄ alkyl andr2 is an integer from 1 to 20, f1 is an integer of 0 to 8, m1, m2, p1and p2 independently of each other are an integer of from 0 to 150,(m1+p1) and (m2+p2) independent of each other are from 2 to 150, L₄, L₅,L₆, L₇, L₈, L₉, L₁₀, L₁₁, L₁₂, L₁₃, L₁₄, L₁₅, L₁₆, L₁₇, Y₈, Y₉, Y₁₀,Y₁₁, Y₁₂, Y₁₃, Y₁₄, Y₁₅, Y₁₆, Y₁₇, Y₁₈, Y₁₉, Y₂₀, Y₂₁, Y₂₂, Y₂₃, Y₂₄,Y₂₅, Y₂₆, Y₂₇, and Y₂₈ independent of one another are a direct bond or adivalent radical of —Z₁—X₂—Z₂—X₃—Z₃—X₄—Z₄— In which X₂, X₃ and X₄independent of one other are a linkage selected from the groupconsisting of a direct bond, —O—, —NR′— in which R′ is H or C₁-C₄ alkyl,—C(O)—NH—, —NH—C(O)—, —NH—C(O)—NH—, —O—C(O)—NH—, —S—, —NH—C(O)—O—,—C(O)—O—, —O—C(O)—, —NH—C(O)—NH—Z₀—NH—C(O)—NH—,—O—C(O)—NH—Z₀—NH—C(O)—O—, —O—C(O)—NH—Z₀—NH—C(O)—NH—, and—NH—C(O)—NH—Z₀—NH—C(O)—O—, Z₀ is a linear or branched C₂-C₁₂ alkylenedivalent radical or a C₅-C₄₅ cycloaliphatic or aliphatic-cycloaliphaticdivalent radical optionally containing therein one or more linkages of—O—, —NR′—, —S— and —C(O)—, Z₁, Z₂, Z₃ and Z₄ independent of one otherare is a direct bond, a linear or branched C₁-C₁₂ alkylene divalentradical optionally containing therein one or more linkages of —O—,—NR′—, —S— and —C(O)—, a divalent radical of —CH₂—CH(OH)—CH₂— or—(CH₂CH₂O)_(r1)—CH₂CH₂— with r1 as defined above, or a C₅-C₄₅cycloaliphatic or aliphatic-cycloaliphatic divalent radical optionallycontaining therein one or more linkages of —O—, —NR′—, —S— and —C(O)—,B₅, B₆, B₇, B₈, B₉, B₁₀, B₁₁, B₁₂, B₁₃, and B₁₄ independent of oneanother are a linear or 3-arm hydrophilic polymer chain having amolecular weight of about 10000 Daltons or less and comprising at leastabout 60% by weight of one or more hydrophilic monomeric units selectedfrom the group consisting of ethyleneoxide units, (meth)acrylamideunits, C₁-C₃ alkyl (meth)acrylamide units, di-(C₁-C₃ alkyl)(meth)acrylamide units, N-vinylpyrrole units, N-vinyl-2-pyrrolidoneunits, 2-vinyloxazoline units, 4-vinylpyridine units, mono-C₁-C₄alkoxy,mono-(meth)acryloyl terminated polyethyleneglycol units having amolecular weight of 600 Daltons or less, di(C₁-C₃ alkyl amino)(C₂-C₄alkyl) (meth)acrylate units, N—C₁-C₄ alkyl-3-methylene-2-pyrrolidoneunits, N—C₁-C₄ alkyl-5-methylene-2-pyrrolidone units, N-vinyl C₁-C₆alkylamide units, N-vinyl-N—C₁-C₆ alkyl amide units, and combinationsthereof, and T₁, T₂, T₃, T₄, T₅, T₆, T₇, T₈, T₉, T₁₀, T₁₁, T₁₂, T₁₃, andT₁₄ independent of one another are an aliphatic or cycloaliphatic oraliphatic-cycloaliphatic trivalent radical which has up to 15 carbonatoms and can be interrupted by —O—, —NR′—, —C(O)— and/or —S—; (b) asolvent selected from the group consisting of water, 1,2-propyleneglycol, a polyethyleneglycol having a molecular weight of about 400Daltons or less, and mixtures thereof, wherein the lens-formingformulation is free of any non-reactive solvent other than water,1,2-propylene glycol, a polyethyleneglycol having a molecular weight ofabout 400 Daltons or less; (2) polymerizing the lens formulation in themold to form a silicone hydrogel contact lens, wherein the formedsilicone hydrogel contact lens has a water content of from about 20% toabout 75% by weight when fully hydrated, an oxygen permeability (Dk) ofat least about 40 barrers, and optionally a hydrophilic surfacecharacterized by an average water contact angle of about 90 degrees orless without post molding surface treatment.
 3. The method of claim 2,further comprising a step of extracting the formed silicone hydrogelcontact lens with water or an aqueous solution.
 4. The method of claim2, wherein the mold is a reusable mold, wherein the lens-formingcomposition is cured actinically under a spatial limitation of actinicradiation to form the silicone hydrogel contact lens, and wherein thereusable mold is cleaned with an ophthalmically compatible solvent. 5.The method of claim 4, wherein the mold is made of quartz, glass,sapphire, CaF₂, a cyclic olefin copolymer, polymethylmethacrylate(PMMA), polyoxymethylene, polyetherimide, and combinations thereof.